VIM: eval

## EVAL

    *eval.txt*	For Vim version 9.1.  Last change: 2025 Sep 25

    		  VIM REFERENCE MANUAL	  by Bram Moolenaar

    Expression evaluation			*expression* *expr* *E15* *eval*
    							*E1002*
    Using expressions is introduced in chapter 41 of the user manual |usr_41|.

    Note: Expression evaluation can be disabled at compile time.  If this has been
    done, the features in this document are not available.  See |+eval| and
    |no-eval-feature|.

    This file is mainly about the backwards compatible (legacy) Vim script.  For
    specifics of Vim9 script, which can execute much faster, supports type
    checking and much more, see |vim9|.  Where the syntax or semantics differ
    a remark is given.

    1.  Variables			|variables|
        1.1 Variable types
        1.2 Function references		|Funcref|
        1.3 Lists				|Lists|
        1.4 Tuples				|Tuples|
        1.5 Dictionaries			|Dictionaries|
        1.6 Blobs				|Blobs|
        1.7 More about variables		|more-variables|
    2.  Expression syntax		|expression-syntax|
    3.  Internal variable		|internal-variables|
    4.  Builtin Functions		|functions|
    5.  Defining functions		|user-functions|
    6.  Curly braces names		|curly-braces-names|
    7.  Commands			|expression-commands|
    8.  Exception handling		|exception-handling|
    9.  Examples			|eval-examples|
    10. Vim script version		|vimscript-version|
    11. No +eval feature		|no-eval-feature|
    12. The sandbox			|eval-sandbox|
    13. Textlock			|textlock|
    14. Vim script library		|vim-script-library|

    Testing support is documented in |testing|.
    Profiling is documented at |profiling|.

    1. Variables						*variables*

    1.1 Variable types
    					*E712* *E896* *E897* *E899* *E1098*
    					*E1107* *E1135* *E1138* *E1523*
    There are eleven types of variables:

    							*Number* *Integer*
    Number		A 32 or 64 bit signed number.  |expr-number|
    		The number of bits is available in |v:numbersize|.
    		Examples:  -123  0x10  0177  0o177 0b1011

    Float		A floating point number. |floating-point-format| *Float*
    		Examples: 123.456  1.15e-6  -1.1e3

    String		A NUL terminated string of 8-bit unsigned characters (bytes).
    		|expr-string| Examples: "ab\txx\"--"  'x-z''a,c'

    List		An ordered sequence of items, see |List| for details.
    		Example: [1, 2, ['a', 'b']]

    Tuple		An ordered immutable sequence of items, see |Tuple| for
    		details.
    		Example: (1, 2, ('a', 'b'))

    Dictionary	An associative, unordered array: Each entry has a key and a
    		value. |Dictionary|
    		Examples:
    			{'blue': "#0000ff", 'red': "#ff0000"}
    			#{blue: "#0000ff", red: "#ff0000"}

    Funcref		A reference to a function |Funcref|.
    		Example: function("strlen")
    		It can be bound to a dictionary and arguments, it then works
    		like a Partial.
    		Example: function("Callback", [arg], myDict)

    Special		|v:false|, |v:true|, |v:none| and |v:null|.  *Special*

    Job		Used for a job, see |job_start()|. *Job* *Jobs*

    Channel		Used for a channel, see |ch_open()|. *Channel* *Channels*

    Blob		Binary Large Object. Stores any sequence of bytes.  See |Blob|
    		for details
    		Example: 0zFF00ED015DAF
    		0z is an empty Blob.

    The Number and String types are converted automatically, depending on how they
    are used.

    Conversion from a Number to a String is by making the ASCII representation of
    the Number.  Examples:
    	Number 123	-->	String "123"
    	Number 0	-->	String "0"
    	Number -1	-->	String "-1"
    							*octal*
    Conversion from a String to a Number only happens in legacy Vim script, not in
    Vim9 script.  It is done by converting the first digits to a number.
    Hexadecimal "0xf9", Octal "017" or "0o17", and Binary "0b10"
    numbers are recognized
    NOTE: when using |Vim9| script or |scriptversion-4| octal with a leading "0"
    is not recognized.  The 0o notation requires patch 8.2.0886.
    If the String doesn't start with digits, the result is zero.
    Examples:
    	String "456"	-->	Number 456
    	String "6bar"	-->	Number 6
    	String "foo"	-->	Number 0
    	String "0xf1"	-->	Number 241
    	String "0100"	-->	Number 64
    	String "0o100"	-->	Number 64
    	String "0b101"	-->	Number 5
    	String "-8"	-->	Number -8
    	String "+8"	-->	Number 0

    To force conversion from String to Number, add zero to it:
    	:echo "0100" + 0
    	64

    To avoid a leading zero to cause octal conversion, or for using a different
    base, use |str2nr()|.

    						*TRUE* *FALSE* *Boolean*
    For boolean operators Numbers are used.  Zero is FALSE, non-zero is TRUE.
    You can also use |v:false| and |v:true|, in Vim9 script |false| and |true|.
    When TRUE is returned from a function it is the Number one, FALSE is the
    number zero.

    Note that in the command:
    	:if "foo"
    	:" NOT executed
    "foo" is converted to 0, which means FALSE.  If the string starts with a
    non-zero number it means TRUE:
    	:if "8foo"
    	:" executed
    To test for a non-empty string, use empty():
    	:if !empty("foo")

    						*falsy* *truthy*
    An expression can be used as a condition, ignoring the type and only using
    whether the value is "sort of true" or "sort of false".  Falsy is:
    	the number zero
    	empty string, blob, list or dictionary
    Other values are truthy.  Examples:
    	0	falsy
    	1	truthy
    	-1	truthy
    	0.0	falsy
    	0.1	truthy
    	''	falsy
    	'x'	truthy
    	[]	falsy
    	[0]	truthy
    	{}	falsy
    	#{x: 1} truthy
    	0z	falsy
    	0z00	truthy

    							*non-zero-arg*
    Function arguments often behave slightly different from |TRUE|: If the
    argument is present and it evaluates to a non-zero Number, |v:true| or a
    non-empty String, then the value is considered to be TRUE.
    Note that " " and "0" are also non-empty strings, thus considered to be TRUE.
    A List, Dictionary or Float is not a Number or String, thus evaluate to FALSE.

    		*E611* *E745* *E728* *E703* *E729* *E730* *E731* *E908* *E910*
    		*E913* *E974* *E975* *E976* *E1319* *E1320* *E1321* *E1322*
    		*E1323* *E1324* *E1520* *E1522*
    |List|, |Tuple|, |Dictionary|, |Funcref|, |Job|, |Channel|, |Blob|, |Class|
    and |object| types are not automatically converted.

    							*E805* *E806* *E808*
    When mixing Number and Float the Number is converted to Float.  Otherwise
    there is no automatic conversion of Float.  You can use str2float() for String
    to Float, printf() for Float to String and float2nr() for Float to Number.

    					*E362* *E891* *E892* *E893* *E894*
    					*E907* *E911* *E914* *E1521*
    When expecting a Float a Number can also be used, but nothing else.

    						*no-type-checking*
    You will not get an error if you try to change the type of a variable.

    1.2 Function references
    					*Funcref* *E695* *E718* *E1192*
    A Funcref variable is obtained with the |function()| function, the |funcref()|
    function, (in |Vim9| script) the name of a function, or created with the
    lambda expression |expr-lambda|.  It can be used in an expression in the place
    of a function name, before the parenthesis around the arguments, to invoke the
    function it refers to.  Example in |Vim9| script:

    	:var Fn = MyFunc
    	:echo Fn()

    Legacy script:
    	:let Fn = function("MyFunc")
    	:echo Fn()
    							*E704* *E705* *E707*
    A Funcref variable must start with a capital, "s:", "w:", "t:" or "b:".  You
    can use "g:" but the following name must still start with a capital.  You
    cannot have both a Funcref variable and a function with the same name.

    A special case is defining a function and directly assigning its Funcref to a
    Dictionary entry.  Example:
    	:function dict.init() dict
    	:   let self.val = 0
    	:endfunction

    The key of the Dictionary can start with a lower case letter.  The actual
    function name is not used here.  Also see |numbered-function|.

    A Funcref can also be used with the |:call| command:
    	:call Fn()
    	:call dict.init()

    The name of the referenced function can be obtained with |string()|.
    	:let func = string(Fn)

    You can use |call()| to invoke a Funcref and use a list variable for the
    arguments:
    	:let r = call(Fn, mylist)

    								*Partial*
    A Funcref optionally binds a Dictionary and/or arguments.  This is also called
    a Partial.  This is created by passing the Dictionary and/or arguments to
    function() or funcref().  When calling the function the Dictionary and/or
    arguments will be passed to the function.  Example:

    	let Cb = function('Callback', ['foo'], myDict)
    	call Cb('bar')

    This will invoke the function as if using:
    	call myDict.Callback('foo', 'bar')

    This is very useful when passing a function around, e.g. in the arguments of
    |ch_open()|.

    Note that binding a function to a Dictionary also happens when the function is
    a member of the Dictionary:

    	let myDict.myFunction = MyFunction
    	call myDict.myFunction()

    Here MyFunction() will get myDict passed as "self".  This happens when the
    "myFunction" member is accessed.  When making assigning "myFunction" to
    otherDict and calling it, it will be bound to otherDict:

    	let otherDict.myFunction = myDict.myFunction
    	call otherDict.myFunction()

    Now "self" will be "otherDict".  But when the dictionary was bound explicitly
    this won't happen:

    	let myDict.myFunction = function(MyFunction, myDict)
    	let otherDict.myFunction = myDict.myFunction
    	call otherDict.myFunction()

    Here "self" will be "myDict", because it was bound explicitly.

    1.3 Lists
    						*list* *List* *Lists* *E686*
    A List is an ordered sequence of items.  An item can be of any type.  Items
    can be accessed by their index number.  Items can be added and removed at any
    position in the sequence.

    List creation
    							*E696* *E697*
    A List is created with a comma-separated sequence of items in square brackets.
    Examples:
    	:let mylist = [1, "two", 3, "four"]
    	:let emptylist = []

    An item can be any expression.  Using a List for an item creates a
    List of Lists:
    	:let nestlist = [[11, 12], [21, 22], [31, 32]]

    An extra comma after the last item is ignored.

    List index
    							*list-index* *E684*
    An item in the List can be accessed by putting the index in square brackets
    after the List.  Indexes are zero-based, thus the first item has index zero.
    	:let item = mylist[0]		" get the first item: 1
    	:let item = mylist[2]		" get the third item: 3

    When the resulting item is a list this can be repeated:
    	:let item = nestlist[0][1]	" get the first list, second item: 12

    A negative index is counted from the end.  Index -1 refers to the last item in
    the List, -2 to the last but one item, etc.
    	:let last = mylist[-1]		" get the last item: "four"

    To avoid an error for an invalid index use the |get()| function.  When an item
    is not available it returns zero or the default value you specify:
    	:echo get(mylist, idx)
    	:echo get(mylist, idx, "NONE")

    List concatenation
    							*list-concatenation*
    Two lists can be concatenated with the "+" operator:
    	:let longlist = mylist + [5, 6]
    	:let longlist = [5, 6] + mylist
    To prepend or append an item, turn it into a list by putting [] around it.

    A list can be concatenated with another one in-place using |:let+=| or
    |extend()|:
    	:let mylist += [7, 8]
    	:call extend(mylist, [7, 8])

    See |list-modification| below for more about changing a list in-place.

    Sublist
    							*sublist*
    A part of the List can be obtained by specifying the first and last index,
    separated by a colon in square brackets:
    	:let shortlist = mylist[2:-1]	" get List [3, "four"]

    Omitting the first index is similar to zero.  Omitting the last index is
    similar to -1.
    	:let endlist = mylist[2:]	" from item 2 to the end: [3, "four"]
    	:let shortlist = mylist[2:2]	" List with one item: [3]
    	:let otherlist = mylist[:]	" make a copy of the List

    Notice that the last index is inclusive.  If you prefer using an exclusive
    index use the |slice()| function.

    If the first index is beyond the last item of the List or the last index is
    before the first item, the result is an empty list.  There is no error
    message.

    If the last index is equal to or greater than the length of the list the
    length minus one is used:
    	:let mylist = [0, 1, 2, 3]
    	:echo mylist[2:8]		" result: [2, 3]

    NOTE: mylist[s:e] means using the variable "s:e" as index.  Watch out for
    using a single letter variable before the ":".  Insert a space when needed:
    mylist[s : e].

    List identity
    							*list-identity*
    When variable "aa" is a list and you assign it to another variable "bb", both
    variables refer to the same list.  Thus changing the list "aa" will also
    change "bb":
    	:let aa = [1, 2, 3]
    	:let bb = aa
    	:call add(aa, 4)
    	:echo bb
    	[1, 2, 3, 4]

    Making a copy of a list is done with the |copy()| function.  Using [:] also
    works, as explained above.  This creates a shallow copy of the list: Changing
    a list item in the list will also change the item in the copied list:
    	:let aa = [[1, 'a'], 2, 3]
    	:let bb = copy(aa)
    	:call add(aa, 4)
    	:let aa[0][1] = 'aaa'
    	:echo aa
    <	[[1, aaa], 2, 3, 4]
    	:echo bb
    	[[1, aaa], 2, 3]

    To make a completely independent list use |deepcopy()|.  This also makes a
    copy of the values in the list, recursively.  Up to a hundred levels deep.

    The operator "is" can be used to check if two variables refer to the same
    List.  "isnot" does the opposite.  In contrast "==" compares if two lists have
    the same value.
    	:let alist = [1, 2, 3]
    	:let blist = [1, 2, 3]
    	:echo alist is blist
    <	0
    	:echo alist == blist
    	1

    Note about comparing lists: Two lists are considered equal if they have the
    same length and all items compare equal, as with using "==".  There is one
    exception: When comparing a number with a string they are considered
    different.  There is no automatic type conversion, as with using "==" on
    variables.  Example:
    	echo 4 == "4"
    <	1
    	echo [4] == ["4"]
    	0

    Thus comparing Lists is more strict than comparing numbers and strings.  You
    can compare simple values this way too by putting them in a list:

    	:let a = 5
    	:let b = "5"
    	:echo a == b
    <	1
    	:echo [a] == [b]
    	0

    List unpack

    To unpack the items in a list to individual variables, put the variables in
    square brackets, like list items:
    	:let [var1, var2] = mylist

    When the number of variables does not match the number of items in the list
    this produces an error.  To handle any extra items from the list append ";"
    and a variable name:
    	:let [var1, var2; rest] = mylist

    This works like:
    	:let var1 = mylist[0]
    	:let var2 = mylist[1]
    	:let rest = mylist[2:]

    Except that there is no error if there are only two items.  "rest" will be an
    empty list then.

    List modification
    							*list-modification*
    To change a specific item of a list use |:let| this way:
    	:let list[4] = "four"
    	:let listlist[0][3] = item

    To change part of a list you can specify the first and last item to be
    modified.  The value must at least have the number of items in the range:
    	:let list[3:5] = [3, 4, 5]

    To add items to a List in-place, you can use |:let+=| (|list-concatenation|):
    	:let listA = [1, 2]
    	:let listA += [3, 4]

    When two variables refer to the same List, changing one List in-place will
    cause the referenced List to be changed in-place:
    	:let listA = [1, 2]
    	:let listB = listA
    	:let listB += [3, 4]
    	:echo listA
    	[1, 2, 3, 4]

    Adding and removing items from a list is done with functions.  Here are a few
    examples:
    	:call insert(list, 'a')		" prepend item 'a'
    	:call insert(list, 'a', 3)	" insert item 'a' before list[3]
    	:call add(list, "new")		" append String item
    	:call add(list, [1, 2])		" append a List as one new item
    	:call extend(list, [1, 2])	" extend the list with two more items
    	:let i = remove(list, 3)	" remove item 3
    	:unlet list[3]			" idem
    	:let l = remove(list, 3, -1)	" remove items 3 to last item
    	:unlet list[3 : ]		" idem
    	:call filter(list, 'v:val !~ "x"')  " remove items with an 'x'

    Changing the order of items in a list:
    	:call sort(list)		" sort a list alphabetically
    	:call reverse(list)		" reverse the order of items
    	:call uniq(sort(list))		" sort and remove duplicates

    For loop

    The |:for| loop executes commands for each item in a List, Tuple, String or
    Blob.  A variable is set to each item in sequence.  Example with a List:
    	:for item in mylist
    	:   call Doit(item)
    	:endfor

    This works like:
    	:let index = 0
    	:while index < len(mylist)
    	:   let item = mylist[index]
    	:   :call Doit(item)
    	:   let index = index + 1
    	:endwhile

    If all you want to do is modify each item in the list then the |map()|
    function will be a simpler method than a for loop.

    Just like the |:let| command, |:for| also accepts a list of variables.  This
    requires the argument to be a List of Lists.
    	:for [lnum, col] in [[1, 3], [2, 8], [3, 0]]
    	:   call Doit(lnum, col)
    	:endfor

    This works like a |:let| command is done for each list item.  Again, the types
    must remain the same to avoid an error.

    It is also possible to put remaining items in a List variable:
    	:for [i, j; rest] in listlist
    	:   call Doit(i, j)
    	:   if !empty(rest)
    	:      echo "remainder: " .. string(rest)
    	:   endif
    	:endfor

    For a Tuple one tuple item at a time is used.

    For a Blob one byte at a time is used.

    For a String one character, including any composing characters, is used as a
    String.  Example:
    	for c in text
    	  echo 'This character is ' .. c
    	endfor

    List functions
    						*E714*
    Functions that are useful with a List:
    	:let r = call(funcname, list)	" call a function with an argument list
    	:if empty(list)			" check if list is empty
    	:let l = len(list)		" number of items in list
    	:let big = max(list)		" maximum value in list
    	:let small = min(list)		" minimum value in list
    	:let xs = count(list, 'x')	" count nr of times 'x' appears in list
    	:let i = index(list, 'x')	" index of first 'x' in list
    	:let lines = getline(1, 10)	" get ten text lines from buffer
    	:call append('$', lines)	" append text lines in buffer
    	:let list = split("a b c")	" create list from items in a string
    	:let string = join(list, ', ')	" create string from list items
    	:let s = string(list)		" String representation of list
    	:call map(list, '">> " .. v:val')  " prepend ">> " to each item

    Don't forget that a combination of features can make things simple.  For
    example, to add up all the numbers in a list:
    	:exe 'let sum = ' .. join(nrlist, '+')

    1.4 Tuples
    						*tuple* *Tuple* *Tuples*
    						*E1532* *E1533*
    A Tuple is an ordered sequence of items.  An item can be of any type.  Items
    can be accessed by their index number.  A Tuple is immutable.

    A Tuple is similar to a List but uses less memory and provides O(1) lookup
    time for an item.

    Tuple creation
    						*E1526* *E1527*
    A Tuple is created with a comma-separated sequence of items in parentheses.
    Examples:
    	:let mytuple = (1, "two", 3, "four")
    	:let tuple = (5,)
    	:let emptytuple = ()

    An item can be any expression.  If there is only one item in the tuple, then
    the item must be followed by a comma.

    Using a Tuple for an item creates a Tuple of Tuples:
    	:let nesttuple = ((11, 12), (21, 22), (31, 32))

    Tuple index
    							*tuple-index* *E1519*
    An item in the Tuple can be accessed by putting the index in square brackets
    after the Tuple.  Indexes are zero-based, thus the first item has index zero.

    	:let item = mytuple[0]		" get the first item: 1
    	:let item = mytuple[2]		" get the third item: 3

    When the resulting item is a tuple this can be repeated:
    	:let item = nesttuple[0][1]	" get the first tuple, second item: 12

    A negative index is counted from the end.  Index -1 refers to the last item in
    the Tuple, -2 to the last but one item, etc.
    	:let last = mytuple[-1]		" get the last item: "four"

    To avoid an error for an invalid index use the |get()| function.  When an item
    is not available it returns zero or the default value you specify:
    	:echo get(mytuple, idx)
    	:echo get(mytuple, idx, "NONE")

    Tuple modification
    							*tuple-modification*
    A tuple is immutable and items cannot be added or removed from a tuple.  But
    List and Dict items within a tuple can be modified:
    	:let tuple = (1, [2, 3], {'a': 4})
    	:let tuple[1][0] = 10
    	:let tuple[2]['a'] = 20

    Tuple concatenation
    							*tuple-concatenation*
    Two tuples can be concatenated with the "+" operator:
    	:let longtuple = mytuple + (5, 6)
    	:let longtuple = (5, 6) + mytuple
    To prepend or append an item, turn it into a tuple by putting () around it.
    The item must be followed by a comma.

    							*E1540*
    Two variadic tuples with same item type can be concatenated but with different
    item types cannot be concatenated.  Examples:
        var a: tuple<...list<number>> = (1, 2)
        var b: tuple<...list<string>> = ('a', 'b')
        echo a + b		# not allowed

        var a: tuple<number, number> = (1, 2)
        var b: tuple<...list<string>> = ('a', 'b')
        echo a + b		# allowed

        var a: tuple<...list<number>> = (1, 2)
        var b: tuple<number, number> = (3, 4)
        echo a + b		# not allowed

        var a: tuple<...list<number>> = (1, 2)
        var b: tuple<number, ...list<number>> = (3, 4)
        echo a + b		# not allowed

    Note that a tuple is immutable and items cannot be added or removed from a
    tuple.

    Subtuple
    							*subtuple*
    A part of the Tuple can be obtained by specifying the first and last index,
    separated by a colon in square brackets:
    	:let shorttuple = mytuple[2:-1]	" get Tuple (3, "four")

    Omitting the first index is similar to zero.  Omitting the last index is
    similar to -1.
    	:let endtuple = mytuple[2:]	" from item 2 to the end: (3, "four")
    	:let shorttuple = mytuple[2:2]	" Tuple with one item: (3,)
    	:let othertuple = mytuple[:]	" make a copy of the Tuple

    Notice that the last index is inclusive.  If you prefer using an exclusive
    index, use the |slice()| function.

    If the first index is beyond the last item of the Tuple or the last index is
    before the first item, the result is an empty tuple.  There is no error
    message.

    If the last index is equal to or greater than the length of the tuple, the
    length minus one is used:
    	:let mytuple = (0, 1, 2, 3)
    	:echo mytuple[2:8]		" result: (2, 3)

    NOTE: mytuple[s:e] means using the variable "s:e" as index.  Watch out for
    using a single letter variable before the ":".  Insert a space when needed:
    mytuple[s : e].

    Tuple identity
    							*tuple-identity*
    When variable "aa" is a tuple and you assign it to another variable "bb", both
    variables refer to the same tuple:
    	:let aa = (1, 2, 3)
    	:let bb = aa

    Making a copy of a tuple is done with the |copy()| function.  Using [:] also
    works, as explained above.  This creates a shallow copy of the tuple: For
    example, changing a list item in the tuple will also change the item in the
    copied tuple:
    	:let aa = ([1, 'a'], 2, 3)
    	:let bb = copy(aa)
    	:let aa[0][1] = 'aaa'
    	:echo aa
    <	([1, aaa], 2, 3)
    	:echo bb
    	([1, aaa], 2, 3)

    To make a completely independent tuple, use |deepcopy()|.  This also makes a
    copy of the values in the tuple, recursively.  Up to a hundred levels deep.

    The operator "is" can be used to check if two variables refer to the same
    Tuple.  "isnot" does the opposite.  In contrast, "==" compares if two tuples
    have the same value.
    	:let atuple = (1, 2, 3)
    	:let btuple = (1, 2, 3)
    	:echo atuple is btuple
    <	0
    	:echo atuple == btuple
    	1

    Note about comparing tuples: Two tuples are considered equal if they have the
    same length and all items compare equal, as with using "==".  There is one
    exception: When comparing a number with a string they are considered
    different.  There is no automatic type conversion, as with using "==" on
    variables.  Example:
    	echo 4 == "4"
    <	1
    	echo (4,) == ("4",)
    	0

    Thus comparing Tuples is more strict than comparing numbers and strings.  You
    can compare simple values this way too by putting them in a tuple:

    	:let a = 5
    	:let b = "5"
    	:echo a == b
    <	1
    	:echo (a,) == (b,)
    	0

    Tuple unpack

    To unpack the items in a tuple to individual variables, put the variables in
    square brackets, like list items:
    	:let [var1, var2] = mytuple

    When the number of variables does not match the number of items in the tuple
    this produces an error.  To handle any extra items from the tuple, append ";"
    and a variable name (which will then be of type tuple):
    	:let [var1, var2; rest] = mytuple

    This works like:
    	:let var1 = mytuple[0]
    	:let var2 = mytuple[1]
    	:let rest = mytuple[2:]

    Except that there is no error if there are only two items.  "rest" will be an
    empty tuple then.

    Tuple functions
    						*E1536*
    Functions that are useful with a Tuple:
    	:let xs = count(tuple, 'x')	" count number of 'x's in tuple
    	:if empty(tuple)		" check if tuple is empty
    	:let i = index(tuple, 'x')	" index of first 'x' in tuple
    	:let l = items(tuple)		" list of items in a tuple
    	:let string = join(tuple, ', ')	" create string from tuple items
    	:let l = len(tuple)		" number of items in tuple
    	:let big = max(tuple)		" maximum value in tuple
    	:let small = min(tuple)		" minimum value in tuple
    	:let r = repeat(tuple, n)	" repeat a tuple n times
    	:let r = reverse(tuple)		" reverse a tuple
    	:let s = slice(tuple, n1, n2)	" slice a tuple
    	:let s = string(tuple)		" String representation of tuple
    	:let l = tuple2list(tuple)	" convert a tuple to list
    	:let t = list2tuple(list)	" convert a list to tuple

    						*E1524*
    A tuple cannot be used with the |map()|, |mapnew()| and |filter()| functions.

    1.5 Dictionaries
    				*dict* *Dict* *Dictionaries* *Dictionary*
    A Dictionary is an associative array: Each entry has a key and a value.  The
    entry can be located with the key.  The entries are stored without a specific
    ordering.

    Dictionary creation
    						*E720* *E721* *E722* *E723*
    A Dictionary is created with a comma-separated sequence of entries in curly
    braces.  Each entry has a key and a value, separated by a colon.  Each key can
    only appear once.  Examples:
    	:let mydict = {'one': 1, 'two': 2, 'three': 3}
    	:let emptydict = {}
    							*E713* *E716* *E717*
    A key is always a String.  You can use a Number, it will be converted to a
    String automatically.  Thus the String '4' and the number 4 will find the same
    entry.  Note that the String '04' and the Number 04 are different, since the
    Number will be converted to the String '4', leading zeros are dropped.  The
    empty string can also be used as a key.

    In |Vim9| script a literal key can be used if it consists only of alphanumeric
    characters, underscore and dash, see |vim9-literal-dict|.
    						*literal-Dict* *#{}*
    To avoid having to put quotes around every key the #{} form can be used in
    legacy script.  This does require the key to consist only of ASCII letters,
    digits, '-' and '_'.  Example:
    	:let mydict = #{zero: 0, one_key: 1, two-key: 2, 333: 3}
    Note that 333 here is the string "333".  Empty keys are not possible with #{}.
    In |Vim9| script the #{} form cannot be used because it can be confused with
    the start of a comment.

    A value can be any expression.  Using a Dictionary for a value creates a
    nested Dictionary:
    	:let nestdict = {1: {11: 'a', 12: 'b'}, 2: {21: 'c'}}

    An extra comma after the last entry is ignored.

    Accessing entries

    The normal way to access an entry is by putting the key in square brackets:
    	:let mydict = {'one': 1, 'two': 2, 'three': 3}
    	:let val = mydict["one"]
    	:let mydict["four"] = 4
    	:let val = mydict.one
    	:let mydict.four = 4

    You can add new entries to an existing Dictionary this way, unlike Lists.

    For keys that consist entirely of letters, digits and underscore the following
    form can be used |expr-entry|:
    	:let val = mydict.one
    	:let mydict.four = 4

    Since an entry can be any type, also a List and a Dictionary, the indexing and
    key lookup can be repeated:
    	:echo dict.key[idx].key

    Dictionary to List conversion

    You may want to loop over the entries in a dictionary.  For this you need to
    turn the Dictionary into a List and pass it to |:for|.

    Most often you want to loop over the keys, using the |keys()| function:
    	:for key in keys(mydict)
    	:   echo key .. ': ' .. mydict[key]
    	:endfor

    The List of keys is unsorted.  You may want to sort them first:
    	:for key in sort(keys(mydict))

    To loop over the values use the |values()| function:
    	:for v in values(mydict)
    	:   echo "value: " .. v
    	:endfor

    If you want both the key and the value use the |items()| function.  It returns
    a List in which each item is a List with two items, the key and the value:
    	:for [key, value] in items(mydict)
    	:   echo key .. ': ' .. value
    	:endfor

    Dictionary identity
    							*dict-identity*
    Just like Lists you need to use |copy()| and |deepcopy()| to make a copy of a
    Dictionary.  Otherwise, assignment results in referring to the same
    Dictionary:
    	:let onedict = {'a': 1, 'b': 2}
    	:let adict = onedict
    	:let adict['a'] = 11
    	:echo onedict['a']
    	11

    Two Dictionaries compare equal if all the key-value pairs compare equal.  For
    more info see |list-identity|.

    Dictionary modification
    							*dict-modification*
    To change an already existing entry of a Dictionary, or to add a new entry,
    use |:let| this way:
    	:let dict[4] = "four"
    	:let dict['one'] = item

    Removing an entry from a Dictionary is done with |remove()| or |:unlet|.
    Three ways to remove the entry with key "aaa" from dict:
    	:let i = remove(dict, 'aaa')
    	:unlet dict.aaa
    	:unlet dict['aaa']

    Merging a Dictionary with another is done with |extend()|:
    	:call extend(adict, bdict)
    This extends adict with all entries from bdict.  Duplicate keys cause entries
    in adict to be overwritten.  An optional third argument can change this.
    Note that the order of entries in a Dictionary is irrelevant, thus don't
    expect ":echo adict" to show the items from bdict after the older entries in
    adict.

    Weeding out entries from a Dictionary can be done with |filter()|:
    	:call filter(dict, 'v:val =~ "x"')
    This removes all entries from "dict" with a value not matching 'x'.
    This can also be used to remove all entries:
    	call filter(dict, 0)

    In some situations it is not allowed to remove or add entries to a Dictionary.
    Especially when iterating over all the entries.  You will get *E1313* or
    another error in that case.

    Dictionary function
    				*Dictionary-function* *self* *E725* *E862*
    When a function is defined with the "dict" attribute it can be used in a
    special way with a dictionary.  Example:
    	:function Mylen() dict
    	:   return len(self.data)
    	:endfunction
    	:let mydict = {'data': [0, 1, 2, 3], 'len': function("Mylen")}
    	:echo mydict.len()

    This is like a method in object oriented programming.  The entry in the
    Dictionary is a |Funcref|.  The local variable "self" refers to the dictionary
    the function was invoked from.  When using |Vim9| script you can use classes
    and objects, see `:class`.

    It is also possible to add a function without the "dict" attribute as a
    Funcref to a Dictionary, but the "self" variable is not available then.

    				*numbered-function* *anonymous-function*
    To avoid the extra name for the function it can be defined and directly
    assigned to a Dictionary in this way:
    	:let mydict = {'data': [0, 1, 2, 3]}
    	:function mydict.len()
    	:   return len(self.data)
    	:endfunction
    	:echo mydict.len()

    The function will then get a number and the value of dict.len is a |Funcref|
    that references this function.  The function can only be used through a
    |Funcref|.  It will automatically be deleted when there is no |Funcref|
    remaining that refers to it.

    It is not necessary to use the "dict" attribute for a numbered function.

    If you get an error for a numbered function, you can find out what it is with
    a trick.  Assuming the function is 42, the command is:
    	:function g:42

    Functions for Dictionaries
    							*E715*
    Functions that can be used with a Dictionary:
    	:if has_key(dict, 'foo')	" TRUE if dict has entry with key "foo"
    	:if empty(dict)			" TRUE if dict is empty
    	:let l = len(dict)		" number of items in dict
    	:let big = max(dict)		" maximum value in dict
    	:let small = min(dict)		" minimum value in dict
    	:let xs = count(dict, 'x')	" count nr of times 'x' appears in dict
    	:let s = string(dict)		" String representation of dict
    	:call map(dict, '">> " .. v:val')  " prepend ">> " to each item

    1.6 Blobs
    						*blob* *Blob* *Blobs* *E978*
    A Blob is a binary object.  It can be used to read an image from a file and
    send it over a channel, for example.

    A Blob mostly behaves like a |List| of numbers, where each number has the
    value of an 8-bit byte, from 0 to 255.

    Blob creation

    A Blob can be created with a |blob-literal|:
    	:let b = 0zFF00ED015DAF
    Dots can be inserted between bytes (pair of hex characters) for readability,
    they don't change the value:
    	:let b = 0zFF00.ED01.5DAF

    A blob can be read from a file with |readfile()| passing the {type} argument
    set to "B", for example:
    	:let b = readfile('image.png', 'B')

    A blob can be read from a channel with the |ch_readblob()| function.

    Blob index
    							*blob-index* *E979*
    A byte in the Blob can be accessed by putting the index in square brackets
    after the Blob.  Indexes are zero-based, thus the first byte has index zero.
    	:let myblob = 0z00112233
    	:let byte = myblob[0]		" get the first byte: 0x00
    	:let byte = myblob[2]		" get the third byte: 0x22

    A negative index is counted from the end.  Index -1 refers to the last byte in
    the Blob, -2 to the last but one byte, etc.
    	:let last = myblob[-1]		" get the last byte: 0x33

    To avoid an error for an invalid index use the |get()| function.  When an item
    is not available it returns -1 or the default value you specify:
    	:echo get(myblob, idx)
    	:echo get(myblob, idx, 999)

    Blob iteration

    The |:for| loop executes commands for each byte of a Blob.  The loop variable
    is set to each byte in the Blob.  Example:
    	:for byte in 0z112233
    	:   call Doit(byte)
    	:endfor
    This calls Doit() with 0x11, 0x22 and 0x33.

    Blob concatenation
    							*blob-concatenation*
    Two blobs can be concatenated with the "+" operator:
    	:let longblob = myblob + 0z4455
    	:let longblob = 0z4455 + myblob

    A blob can be concatenated with another one in-place using |:let+=|:
    	:let myblob += 0z6677

    See |blob-modification| below for more about changing a blob in-place.

    Part of a blob

    A part of the Blob can be obtained by specifying the first and last index,
    separated by a colon in square brackets:
    	:let myblob = 0z00112233
    	:let shortblob = myblob[1:2]	" get 0z1122
    	:let shortblob = myblob[2:-1]	" get 0z2233

    Omitting the first index is similar to zero.  Omitting the last index is
    similar to -1.
    	:let endblob = myblob[2:]	" from item 2 to the end: 0z2233
    	:let shortblob = myblob[2:2]	" Blob with one byte: 0z22
    	:let otherblob = myblob[:]	" make a copy of the Blob

    If the first index is beyond the last byte of the Blob or the second index is
    before the first index, the result is an empty Blob.  There is no error
    message.

    If the second index is equal to or greater than the length of the list the
    length minus one is used:
    	:echo myblob[2:8]		" result: 0z2233

    Blob modification
    						*blob-modification* *E1184*
    To change a specific byte of a blob use |:let| this way:
    	:let blob[4] = 0x44

    When the index is just one beyond the end of the Blob, it is appended. Any
    higher index is an error.

    To change a sequence of bytes the [:] notation can be used:
    	let blob[1:3] = 0z445566
    The length of the replaced bytes must be exactly the same as the value
    provided. *E972*

    To change part of a blob you can specify the first and last byte to be
    modified.  The value must have the same number of bytes in the range:
    	:let blob[3:5] = 0z334455

    To add items to a Blob in-place, you can use |:let+=| (|blob-concatenation|):
    	:let blobA = 0z1122
    	:let blobA += 0z3344

    When two variables refer to the same Blob, changing one Blob in-place will
    cause the referenced Blob to be changed in-place:
    	:let blobA = 0z1122
    	:let blobB = blobA
    	:let blobB += 0z3344
    	:echo blobA
    	0z11223344

    You can also use the functions |add()|, |remove()| and |insert()|.

    Blob identity

    Blobs can be compared for equality:
    	if blob == 0z001122
    And for equal identity:
    	if blob is otherblob
    							*blob-identity* *E977*
    When variable "aa" is a Blob and you assign it to another variable "bb", both
    variables refer to the same Blob.  Then the "is" operator returns true.

    When making a copy using [:] or |copy()| the values are the same, but the
    identity is different:
    	:let blob = 0z112233
    	:let blob2 = blob
    	:echo blob == blob2
    <	1
    	:echo blob is blob2
    <	1
    	:let blob3 = blob[:]
    	:echo blob == blob3
    <	1
    	:echo blob is blob3
    	0

    Making a copy of a Blob is done with the |copy()| function.  Using [:] also
    works, as explained above.

    1.7 More about variables
    							*more-variables*
    If you need to know the type of a variable or expression, use the |type()|
    function.

    When the '!' flag is included in the 'viminfo' option, global variables that
    start with an uppercase letter, and don't contain a lowercase letter, are
    stored in the viminfo file |viminfo-file|.

    When the 'sessionoptions' option contains "global", global variables that
    start with an uppercase letter and contain at least one lowercase letter are
    stored in the session file |session-file|.

    variable name		can be stored where
    my_var_6		not
    My_Var_6		session file
    MY_VAR_6		viminfo file

    In legacy script it is possible to form a variable name with curly braces, see
    |curly-braces-names|.

    2. Expression syntax					*expression-syntax*
    							*E1143*
    Expression syntax summary, from least to most significant:

    |expr1|	expr2
    	expr2 ? expr1 : expr1	if-then-else

    |expr2|	expr3
    	expr3 || expr3 ...	logical OR

    |expr3|	expr4
    	expr4 && expr4 ...	logical AND

    |expr4|	expr5
    	expr5 == expr5		equal
    	expr5 != expr5		not equal
    	expr5 >	 expr5		greater than
    	expr5 >= expr5		greater than or equal
    	expr5 <	 expr5		smaller than
    	expr5 <= expr5		smaller than or equal
    	expr5 =~ expr5		regexp matches
    	expr5 !~ expr5		regexp doesn't match

    	expr5 ==? expr5		equal, ignoring case
    	expr5 ==# expr5		equal, match case
    	etc.			As above, append ? for ignoring case, # for
    				matching case

    	expr5 is expr5		same |List|, |Tuple|, |Dictionary| or |Blob|
    				instance
    	expr5 isnot expr5	different |List|, |Tuple|, |Dictionary| or
    				|Blob| instance

    |expr5|	expr6
    	expr6 << expr6		bitwise left shift
    	expr6 >> expr6		bitwise right shift

    |expr6|	expr7
    	expr7 +	 expr7 ...	number addition, list or tuple or blob
    				concatenation
    	expr7 -	 expr7 ...	number subtraction
    	expr7 .	 expr7 ...	string concatenation
    	expr7 .. expr7 ...	string concatenation

    |expr7|	expr8
    	expr8 *	 expr8 ...	number multiplication
    	expr8 /	 expr8 ...	number division
    	expr8 %	 expr8 ...	number modulo

    |expr8|	expr9
    	<type>expr9		type check and conversion (|Vim9| only)

    |expr9|	expr10
    	! expr9			logical NOT
    	- expr9			unary minus
    	+ expr9			unary plus

    |expr10|  expr11
    	expr10[expr1]		byte of a String or item of a |List| or
    				|Tuple|
    	expr10[expr1 : expr1]	substring of a String or sublist of a |List|
    				or a slice of a |Tuple|
    	expr10.name		entry in a |Dictionary|
    	expr10(expr1, ...)	function call with |Funcref| variable
    	expr10->name(expr1, ...)	|method| call

    |expr11|  number		number constant
    	"string"		string constant, backslash is special
    	'string'		string constant, ' is doubled
    	[expr1, ...]		|List|
    	(expr1, ...)		|Tuple|
    	{expr1: expr1, ...}	|Dictionary|
    	#{key: expr1, ...}	legacy |Dictionary|
    	&option			option value
    	(expr1)			nested expression
    	variable		internal variable
    	va{ria}ble		internal variable with curly braces
    	$VAR			environment variable
    	@r			contents of register 'r'
    	function(expr1, ...)	function call
    	func{ti}on(expr1, ...)	function call with curly braces
    	{args -> expr1}		legacy lambda expression
    	(args) => expr1		Vim9 lambda expression

    "..." indicates that the operations in this level can be concatenated.
    Example:
    	&nu || &list && &shell == "csh"

    All expressions within one level are parsed from left to right.

    Expression nesting is limited to 1000 levels deep (300 when build with MSVC)
    to avoid running out of stack and crashing. *E1169*

    expr1				*expr1* *ternary* *falsy-operator* *??* *E109*

    The ternary operator: expr2 ? expr1 : expr1
    The falsy operator:   expr2 ?? expr1

    Ternary operator

    In legacy script the expression before the '?' is evaluated to a number.  If
    it evaluates to |TRUE|, the result is the value of the expression between the
    '?' and ':', otherwise the result is the value of the expression after the
    ':'.

    In |Vim9| script the first expression must evaluate to a boolean, see
    |vim9-boolean|.

    Example:
    	:echo lnum == 1 ? "top" : lnum

    Since the first expression is an "expr2", it cannot contain another ?:.  The
    other two expressions can, thus allow for recursive use of ?:.
    Example:
    	:echo lnum == 1 ? "top" : lnum == 1000 ? "last" : lnum

    To keep this readable, using |line-continuation| is suggested:
    	:echo lnum == 1
    	:\	? "top"
    	:\	: lnum == 1000
    	:\		? "last"
    	:\		: lnum

    You should always put a space before the ':', otherwise it can be mistaken for
    use in a variable such as "a:1".

    Falsy operator

    This is also known as the "null coalescing operator", but that's too
    complicated, thus we just call it the falsy operator.

    The expression before the '??' is evaluated.  If it evaluates to
    |truthy|, this is used as the result.  Otherwise the expression after the '??'
    is evaluated and used as the result.  This is most useful to have a default
    value for an expression that may result in zero or empty:
    	echo theList ?? 'list is empty'
    	echo GetName() ?? 'unknown'

    These are similar, but not equal:
    	expr2 ?? expr1
    	expr2 ? expr2 : expr1
    In the second line "expr2" is evaluated twice.  And in |Vim9| script the type
    of expr2 before "?" must be a boolean.

    expr2 and expr3						*expr2* *expr3*

    expr3 || expr3 ..	logical OR		*expr-barbar*
    expr4 && expr4 ..	logical AND		*expr-&&*

    The "||" and "&&" operators take one argument on each side.

    In legacy script the arguments are (converted to) Numbers.

    In |Vim9| script the values must be boolean, see |vim9-boolean|.  Use "!!" to
    convert any type to a boolean.

    The result is:
        input			 output
    n1	n2		n1 || n2	n1 && n2
    |FALSE|	|FALSE|		|FALSE|		|FALSE|
    |FALSE|	|TRUE|		|TRUE|		|FALSE|
    |TRUE|	|FALSE|		|TRUE|		|FALSE|
    |TRUE|	|TRUE|		|TRUE|		|TRUE|

    The operators can be concatenated, for example:

    	&nu || &list && &shell == "csh"

    Note that "&&" takes precedence over "||", so this has the meaning of:

    	&nu || (&list && &shell == "csh")

    Once the result is known, the expression "short-circuits", that is, further
    arguments are not evaluated.  This is like what happens in C.  For example:

    	let a = 1
    	echo a || b

    This is valid even if there is no variable called "b" because "a" is |TRUE|,
    so the result must be |TRUE|.  Similarly below:

    	echo exists("b") && b == "yes"

    This is valid whether "b" has been defined or not.  The second clause will
    only be evaluated if "b" has been defined.

    expr4							*expr4* *E1153*

    expr5 {cmp} expr5

    Compare two expr5 expressions.  In legacy script the result is a 0 if it
    evaluates to false, or 1 if it evaluates to true.  In |Vim9| script the result
    is |true| or |false|.

    			*expr-==*  *expr-!=*  *expr->*	 *expr->=*
    			*expr-<*   *expr-<=*  *expr-=~*  *expr-!~*
    			*expr-==#* *expr-!=#* *expr->#*  *expr->=#*
    			*expr-<#*  *expr-<=#* *expr-=~#* *expr-!~#*
    			*expr-==?* *expr-!=?* *expr->?*  *expr->=?*
    			*expr-<?*  *expr-<=?* *expr-=~?* *expr-!~?*
    			*expr-is* *expr-isnot* *expr-is#* *expr-isnot#*
    			*expr-is?* *expr-isnot?* *E1072*
    		use 'ignorecase'    match case	   ignore case
    equal			==		==#		==?
    not equal		!=		!=#		!=?
    greater than		>		>#		>?
    greater than or equal	>=		>=#		>=?
    smaller than		<		<#		<?
    smaller than or equal	<=		<=#		<=?
    regexp matches		=~		=~#		=~?
    regexp doesn't match	!~		!~#		!~?
    same instance		is		is#		is?
    different instance	isnot		isnot#		isnot?

    Examples:
    "abc" ==# "Abc"	  evaluates to 0
    "abc" ==? "Abc"	  evaluates to 1
    "abc" == "Abc"	  evaluates to 1 if 'ignorecase' is set, 0 otherwise
    NOTE: In |Vim9| script 'ignorecase' is not used.

    						*E691* *E692* *E1517* *E1518*
    A |List| can only be compared with a |List| and only "equal", "not equal",
    "is" and "isnot" can be used.  This compares the values of the list,
    recursively.  Ignoring case means case is ignored when comparing item values.
    Same applies for a |Tuple|.

    							*E735* *E736*
    A |Dictionary| can only be compared with a |Dictionary| and only "equal", "not
    equal", "is" and "isnot" can be used.  This compares the key/values of the
    |Dictionary| recursively.  Ignoring case means case is ignored when comparing
    item values.

    							*E694*
    A |Funcref| can only be compared with a |Funcref| and only "equal", "not
    equal", "is" and "isnot" can be used.  Case is never ignored.  Whether
    arguments or a Dictionary are bound (with a partial) matters.  The
    Dictionaries must also be equal (or the same, in case of "is") and the
    arguments must be equal (or the same).

    To compare Funcrefs to see if they refer to the same function, ignoring bound
    Dictionary and arguments, use |get()| to get the function name:
    	if get(Part1, 'name') == get(Part2, 'name')
    	   " Part1 and Part2 refer to the same function
    							*E1037*
    Using "is" or "isnot" with a |List|, |Tuple|, |Dictionary| or |Blob| checks
    whether the expressions are referring to the same |List|, |Tuple|,
    |Dictionary| or |Blob| instance.  A copy of a |List| or |Tuple| is different
    from the original |List| or |Tuple|.  When using "is" without a |List|,
    |Tuple|, |Dictionary| or |Blob|, it is equivalent to using "equal", using
    "isnot" is equivalent to using "not equal".  Except that a different type
    means the values are different:
    	echo 4 == '4'
    	1
    	echo 4 is '4'
    	0
    	echo 0 is []
    	0
    "is#"/"isnot#" and "is?"/"isnot?" can be used to match and ignore case.
    In |Vim9| script this doesn't work, two strings are never identical.

    In legacy script, when comparing a String with a Number, the String is
    converted to a Number, and the comparison is done on Numbers.  This means
    that:
    	echo 0 == 'x'
    	1
    because 'x' converted to a Number is zero.  However:
    	echo [0] == ['x']
    	0
    Inside a List or Tuple or Dictionary this conversion is not used.

    In |Vim9| script the types must match.

    When comparing two Strings, this is done with strcmp() or stricmp().  This
    results in the mathematical difference (comparing byte values), not
    necessarily the alphabetical difference in the local language.

    When using the operators with a trailing '#', or the short version and
    'ignorecase' is off, the comparing is done with strcmp(): case matters.

    When using the operators with a trailing '?', or the short version and
    'ignorecase' is set, the comparing is done with stricmp(): case is ignored.

    'smartcase' is not used.

    The "=~" and "!~" operators match the lefthand argument with the righthand
    argument, which is used as a pattern.  See |pattern| for what a pattern is.
    This matching is always done like 'magic' was set and 'cpoptions' is empty, no
    matter what the actual value of 'magic' or 'cpoptions' is.  This makes scripts
    portable.  To avoid backslashes in the regexp pattern to be doubled, use a
    single-quote string, see |literal-string|.
    Since a string is considered to be a single line, a multi-line pattern
    (containing \n, backslash-n) will not match.  However, a literal NL character
    can be matched like an ordinary character.  Examples:
    	"foo\nbar" =~ "\n"	evaluates to 1
    	"foo\nbar" =~ "\\n"	evaluates to 0

    expr5						*expr5* *bitwise-shift*

    expr6 << expr6	bitwise left shift				*expr-<<*
    expr6 >> expr6	bitwise right shift				*expr->>*
    							*E1282* *E1283*
    The "<<" and ">>" operators can be used to perform bitwise left or right shift
    of the left operand by the number of bits specified by the right operand.  The
    operands are used as positive numbers.  When shifting right with ">>" the
    topmost bit (sometimes called the sign bit) is cleared.  If the right operand
    (shift amount) is more than the maximum number of bits in a number
    (|v:numbersize|) the result is zero.

    expr6 and expr7				*expr6* *expr7* *E1036* *E1051*

    								*expr-+*
    expr7 + expr7   Number addition, |List| or |Tuple| or |Blob| concatenation
    expr7 - expr7   Number subtraction				*expr--*
    expr7 . expr7   String concatenation				*expr-.*
    expr7 .. expr7  String concatenation				*expr-..*

    For |Lists| only "+" is possible and then both expr7 must be a list.  The
    result is a new list with the two lists concatenated.  Same for a |Tuple|.

    For String concatenation ".." is preferred, since "." is ambiguous, it is also
    used for |Dict| member access and floating point numbers.
    In |Vim9| script and when |vimscript-version| is 2 or higher, using "." is not
    allowed.

    In |Vim9| script the arguments of ".." are converted to String for simple
    types: Number, Float, Special and Bool.  For other types |string()| should be
    used.

    expr8 * expr8  Number multiplication				*expr-star*
    expr8 / expr8  Number division					*expr-/*
    expr8 % expr8  Number modulo					*expr-%*

    In legacy script, for all operators except "." and "..", Strings are converted
    to Numbers.

    For bitwise operators see |and()|, |or()| and |xor()|.

    Note the difference between "+" and ".." in legacy script:
    	"123" + "456" = 579
    	"123" .. "456" = "123456"

    Since '..' has the same precedence as '+' and '-', you need to read:
    	1 .. 90 + 90.0
    As:
    	(1 .. 90) + 90.0
    That works in legacy script, since the String "190" is automatically converted
    to the Number 190, which can be added to the Float 90.0.  However:
    	1 .. 90 * 90.0
    Should be read as:
    	1 .. (90 * 90.0)
    Since '..' has lower precedence than '*'.  This does NOT work, since this
    attempts to concatenate a Float and a String.

    When dividing a Number by zero the result depends on the value:
    	  0 / 0  = -0x80000000	(like NaN for Float)
    	 >0 / 0  =  0x7fffffff	(like positive infinity)
    	 <0 / 0  = -0x7fffffff	(like negative infinity)
    	(before Vim 7.2 it was always 0x7fffffff)
    In |Vim9| script dividing a number by zero is an error.	*E1154*

    When 64-bit Number support is enabled:
    	  0 / 0  = -0x8000000000000000	(like NaN for Float)
    	 >0 / 0  =  0x7fffffffffffffff	(like positive infinity)
    	 <0 / 0  = -0x7fffffffffffffff	(like negative infinity)

    When the righthand side of '%' is zero, the result is 0.

    None of these work for |Funcref|s.

    ".", ".." and "%" do not work for Float. *E804* *E1035*

    expr8							*expr8*

    <type>expr9

    This is only available in |Vim9| script, see |type-casting|.

    expr9							*expr9*

    ! expr9			logical NOT		*expr-!*
    - expr9			unary minus		*expr-unary--*
    + expr9			unary plus		*expr-unary-+*

    For '!' |TRUE| becomes |FALSE|, |FALSE| becomes |TRUE| (one).
    For '-' the sign of the number is changed.
    For '+' the number is unchanged.  Note: "++" has no effect.

    In legacy script a String will be converted to a Number first.  Note that if
    the string does not start with a digit you likely don't get what you expect.

    In |Vim9| script an error is given when "-" or "+" is used and the type is not
    a number.

    In |Vim9| script "!" can be used for any type and the result is always a
    boolean.  Use "!!" to convert any type to a boolean, according to whether the
    value is |falsy|.

    These three can be repeated and mixed.  Examples:
    	!-1	    == 0
    	!!8	    == 1
    	--9	    == 9

    expr10							*expr10*

    This expression is either |expr11| or a sequence of the alternatives below,
    in any order.  E.g., these are all possible:
    	expr10[expr1].name
    	expr10.name[expr1]
    	expr10(expr1, ...)[expr1].name
    	expr10->(expr1, ...)[expr1]
    Evaluation is always from left to right.

    							*expr-[]* *E111*
    expr10[expr1]		item of String or |List| or |Tuple|
    						*E909* *subscript* *E1062*
    In legacy Vim script:
    If expr10 is a Number or String this results in a String that contains the
    expr1'th single byte from expr10.  expr10 is used as a String (a number is
    automatically converted to a String), expr1 as a Number.  This doesn't
    recognize multibyte encodings, see `byteidx()` for an alternative, or use
    `split()` to turn the string into a list of characters.  Example, to get the
    byte under the cursor:
    	:let c = getline(".")[col(".") - 1]

    In |Vim9| script:					*E1147* *E1148*
    If expr10 is a String this results in a String that contains the expr1'th
    single character (including any composing characters) from expr10.  To use byte
    indexes use |strpart()|.

    Index zero gives the first byte or character.  Careful: text column numbers
    start with one!

    If the length of the String is less than the index, the result is an empty
    String.  A negative index always results in an empty string (reason: backward
    compatibility).  Use [-1:] to get the last byte or character.
    In Vim9 script a negative index is used like with a list: count from the end.

    If expr10 is a |List| then it results the item at index expr1.  See
    |list-index| for possible index values.  If the index is out of range this
    results in an error.  Example:
    	:let item = mylist[-1]		" get last item

    Generally, if a |List| index is equal to or higher than the length of the
    |List|, or more negative than the length of the |List|, this results in an
    error.

    A |Tuple| index is similar to a |List| index as explained above.

    expr10[expr1a : expr1b]	substring or |sublist|		*expr-[:]* *substring*

    If expr10 is a String this results in the substring with the bytes or
    characters from expr1a to and including expr1b.  expr10 is used as a String,
    expr1a and expr1b are used as a Number.

    In legacy Vim script the indexes are byte indexes.  This doesn't recognize
    multibyte encodings, see |byteidx()| for computing the indexes.  If expr10 is
    a Number it is first converted to a String.

    In Vim9 script the indexes are character indexes and include composing
    characters.  To use byte indexes use |strpart()|.  To use character indexes
    without including composing characters use |strcharpart()|.

    The item at index expr1b is included, it is inclusive.  For an exclusive index
    use the |slice()| function.

    If expr1a is omitted zero is used.  If expr1b is omitted the length of the
    string minus one is used.

    A negative number can be used to measure from the end of the string.  -1 is
    the last character, -2 the last but one, etc.

    If an index goes out of range for the string characters are omitted.  If
    expr1b is smaller than expr1a the result is an empty string.

    Examples:
    	:let c = name[-1:]		" last byte of a string
    	:let c = name[0:-1]		" the whole string
    	:let c = name[-2:-2]		" last but one byte of a string
    	:let s = line(".")[4:]		" from the fifth byte to the end
    	:let s = s[:-3]			" remove last two bytes

    							*slice*
    If expr10 is a |List| this results in a new |List| with the items indicated by
    the indexes expr1a and expr1b.  This works like with a String, as explained
    just above. Also see |sublist| below.  Examples:
    	:let l = mylist[:3]		" first four items
    	:let l = mylist[4:4]		" List with one item
    	:let l = mylist[:]		" shallow copy of a List
    A |Tuple| slice is similar to a |List| slice.

    If expr10 is a |Blob| this results in a new |Blob| with the bytes in the
    indexes expr1a and expr1b, inclusive.  Examples:
    	:let b = 0zDEADBEEF
    	:let bs = b[1:2]		" 0zADBE
    	:let bs = b[:]			" copy of 0zDEADBEEF

    Using expr10[expr1] or expr10[expr1a : expr1b] on a |Funcref| results in an
    error.

    Watch out for confusion between a namespace and a variable followed by a colon
    for a sublist:
    	mylist[n:]     " uses variable n
    	mylist[s:]     " uses namespace s:, error!

    expr10.name		entry in a |Dictionary|		*expr-entry*
    							*E1203* *E1229*
    If expr10 is a |Dictionary| and it is followed by a dot, then the following
    name will be used as a key in the |Dictionary|.  This is just like:
    expr10[name].

    The name must consist of alphanumeric characters, just like a variable name,
    but it may start with a number.  Curly braces cannot be used.

    There must not be white space before or after the dot.

    Examples:
    	:let dict = {"one": 1, 2: "two"}
    	:echo dict.one		" shows "1"
    	:echo dict.2		" shows "two"
    	:echo dict .2		" error because of space before the dot

    Note that the dot is also used for String concatenation.  To avoid confusion
    always put spaces around the dot for String concatenation.

    expr10(expr1, ...)	|Funcref| function call		*E1085*

    When expr10 is a |Funcref| type variable, invoke the function it refers to.

    expr10->name([args])	method call			*method* *->*
    expr10->{lambda}([args])
    							*E260* *E276* *E1265*
    For methods that are also available as global functions this is the same as:
    	name(expr10 [, args])
    There can also be methods specifically for the type of "expr10".

    This allows for chaining, passing the value that one method returns to the
    next method:
    	mylist->filter(filterexpr)->map(mapexpr)->sort()->join()

    Example of using a lambda:
    	GetPercentage()->{x -> x * 100}()->printf('%d%%')

    When using -> the |expr9| operators will be applied first, thus:
    	-1.234->string()
    Is equivalent to:
    	(-1.234)->string()
    And NOT:
    	-(1.234->string())

    What comes after "->" can be a name, a simple expression (not containing any
    parenthesis), or any expression in parentheses:
    	base->name(args)
    	base->some.name(args)
    	base->alist[idx](args)
    	base->(getFuncRef())(args)
    Note that in the last call the base is passed to the function resulting from
    "(getFuncRef())", inserted before "args".  *E1275*

    							*E274*
    "->name(" must not contain white space.  There can be white space before the
    "->" and after the "(", thus you can split the lines like this:
    	mylist
    	\ ->filter(filterexpr)
    	\ ->map(mapexpr)
    	\ ->sort()
    	\ ->join()

    When using the lambda form there must be no white space between the } and the
    (.

    							*expr11*
    number

    number			number constant			*expr-number*

    			*0x* *hex-number* *0o* *octal-number* *binary-number*
    Decimal, Hexadecimal (starting with 0x or 0X), Binary (starting with 0b or 0B)
    and Octal (starting with 0, 0o or 0O).

    Assuming 64 bit numbers are used (see |v:numbersize|) an unsigned number is
    truncated to 0x7fffffffffffffff or 9223372036854775807.  You can use -1 to get
    0xffffffffffffffff.

    						*floating-point-format*
    Floating point numbers can be written in two forms:

    	[-+]{N}.{M}
    	[-+]{N}.{M}[eE][-+]{exp}

    {N} and {M} are numbers.  Both {N} and {M} must be present and can only
    contain digits, except that in |Vim9| script in {N} single quotes between
    digits are ignored.
    [-+] means there is an optional plus or minus sign.
    {exp} is the exponent, power of 10.
    Only a decimal point is accepted, not a comma.  No matter what the current
    locale is.

    Examples:
    	123.456
    	+0.0001
    	55.0
    	-0.123
    	1.234e03
    	1.0E-6
    	-3.1416e+88

    These are INVALID:
    	3.		empty {M}
    	1e40		missing .{M}

    Rationale:
    Before floating point was introduced, the text "123.456" was interpreted as
    the two numbers "123" and "456", both converted to a string and concatenated,
    resulting in the string "123456".  Since this was considered pointless, and we
    could not find it intentionally being used in Vim scripts, this backwards
    incompatibility was accepted in favor of being able to use the normal notation
    for floating point numbers.

    							*float-pi* *float-e*
    A few useful values to copy&paste:
    	:let pi = 3.14159265359
    	:let e  = 2.71828182846
    Or, if you don't want to write them in as floating-point literals, you can
    also use functions, like the following:
    	:let pi = acos(-1.0)
    	:let e  = exp(1.0)

    						*floating-point-precision*
    The precision and range of floating points numbers depends on what "double"
    means in the library Vim was compiled with.  There is no way to change this at
    runtime.

    The default for displaying a |Float| is to use 6 decimal places, like using
    printf("%g", f).  You can select something else when using the |printf()|
    function.  Example:
    	:echo printf('%.15e', atan(1))
    	7.853981633974483e-01

    string					*string* *String* *expr-string* *E114*

    "string"		string constant		*expr-quote*

    Note that double quotes are used.

    A string constant accepts these special characters:
    \...	three-digit octal number (e.g., "\316")
    \..	two-digit octal number (must be followed by non-digit)
    \.	one-digit octal number (must be followed by non-digit)
    \x..	byte specified with two hex numbers (e.g., "\x1f")
    \x.	byte specified with one hex number (must be followed by non-hex char)
    \X..	same as \x..
    \X.	same as \x.
    \u....	character specified with up to 4 hex numbers, stored according to the
    	current value of 'encoding' (e.g., "\u02a4")
    \U....	same as \u but allows up to 8 hex numbers.
    \b	backspace <BS>
    \e	escape <Esc>
    \f	formfeed 0x0C
    \n	newline <NL>
    \r	return <CR>
    \t	tab <Tab>
    \\	backslash
    \"	double quote
    \<xxx>	Special key named "xxx".  e.g. "\<C-W>" for CTRL-W.  This is for use
    	in mappings, the 0x80 byte is escaped.
    	To use the double quote character it must be escaped: "<M-\">".
    	Don't use <Char-xxxx> to get a UTF-8 character, use \uxxxx as
    	mentioned above.
    \<*xxx>	Like \<xxx> but prepends a modifier instead of including it in the
    	character.  E.g. "\<C-w>" is one character 0x17 while "\<*C-w>" is four
    	bytes: 3 for the CTRL modifier and then character "W".

    Note that "\xff" is stored as the byte 255, which may be invalid in some
    encodings.  Use "\u00ff" to store character 255 according to the current value
    of 'encoding'.

    Note that "\000" and "\x00" force the end of the string.

    blob-literal				*blob-literal* *E973*

    Hexadecimal starting with 0z or 0Z, with an arbitrary number of bytes.
    The sequence must be an even number of hex characters.  Example:
    	:let b = 0zFF00ED015DAF

    literal-string						*literal-string* *E115*

    'string'		string constant			*expr-'*

    Note that single quotes are used.

    This string is taken as it is.  No backslashes are removed or have a special
    meaning.  The only exception is that two quotes stand for one quote.

    Single quoted strings are useful for patterns, so that backslashes do not need
    to be doubled.  These two commands are equivalent:
    	if a =~ "\\s*"
    	if a =~ '\s*'

    interpolated-string				*$quote* *interpolated-string*

    $"string"		interpolated string constant		*expr-$quote*
    $'string'		interpolated literal string constant	*expr-$'*

    Interpolated strings are an extension of the |string| and |literal-string|,
    allowing the inclusion of Vim script expressions (see |expr1|).  Any
    expression returning a value can be enclosed between curly braces.  The value
    is converted to a string.  All the text and results of the expressions
    are concatenated to make a new string.
    							*E1278* *E1279*
    To include an opening brace '{' or closing brace '}' in the string content
    double it.  For double quoted strings using a backslash also works.  A single
    closing brace '}' will result in an error.

    Examples:
    	let your_name = input("What's your name? ")
    	What's your name?  Peter

    	echo
    	echo $"Hello, {your_name}!"
    	Hello, Peter!

    	echo $"The square root of {{9}} is {sqrt(9)}"
    	The square root of {9} is 3.0

    						*string-offset-encoding*
    A string consists of multiple characters.  How the characters are stored
    depends on 'encoding'.  Most common is UTF-8, which uses one byte for ASCII
    characters, two bytes for other latin characters and more bytes for other
    characters.

    A string offset can count characters or bytes.  Other programs may use
    UTF-16 encoding (16-bit words) and an offset of UTF-16 words.  Some functions
    use byte offsets, usually for UTF-8 encoding.  Other functions use character
    offsets, in which case the encoding doesn't matter.

    The different offsets for the string "a©😊" are below:

      UTF-8 offsets:
          [0]: 61, [1]: C2, [2]: A9, [3]: F0, [4]: 9F, [5]: 98, [6]: 8A
      UTF-16 offsets:
          [0]: 0061, [1]: 00A9, [2]: D83D, [3]: DE0A
      UTF-32 (character) offsets:
          [0]: 00000061, [1]: 000000A9, [2]: 0001F60A

    You can use the "g8" and "ga" commands on a character to see the
    decimal/hex/octal values.

    The functions |byteidx()|, |utf16idx()| and |charidx()| can be used to convert
    between these indices.  The functions |strlen()|, |strutf16len()| and
    |strcharlen()| return the number of bytes, UTF-16 code units and characters in
    a string respectively.

    option						*expr-option* *E112* *E113*

    &option			option value, local value if possible
    &g:option		global option value
    &l:option		local option value

    Examples:
    	echo "tabstop is " .. &tabstop
    	if &insertmode

    Any option name can be used here.  See |options|.  When using the local value
    and there is no buffer-local or window-local value, the global value is used
    anyway.

    register						*expr-register* *@r*

    @r			contents of register 'r'

    The result is the contents of the named register, as a single string.
    Newlines are inserted where required.  To get the contents of the unnamed
    register use @" or @@.  See |registers| for an explanation of the available
    registers.

    When using the '=' register you get the expression itself, not what it
    evaluates to.  Use |eval()| to evaluate it.

    nesting						*expr-nesting* *E110*

    (expr1)			nested expression

    environment variable					*expr-env*

    $VAR			environment variable

    The String value of any environment variable.  When it is not defined, the
    result is an empty string.

    The functions `getenv()` and `setenv()` can also be used and work for
    environment variables with non-alphanumeric names.
    The function `environ()` can be used to get a Dict with all environment
    variables.

    						*expr-env-expand*
    Note that there is a difference between using $VAR directly and using
    expand("$VAR").  Using it directly will only expand environment variables that
    are known inside the current Vim session.  Using expand() will first try using
    the environment variables known inside the current Vim session.  If that
    fails, a shell will be used to expand the variable.  This can be slow, but it
    does expand all variables that the shell knows about.  Example:
    	:echo $shell
    	:echo expand("$shell")
    The first one probably doesn't echo anything, the second echoes the $shell
    variable (if your shell supports it).

    internal variable			*expr-variable* *E1015* *E1089*

    variable		internal variable
    See below |internal-variables|.

    function call		*expr-function* *E116* *E118* *E119* *E120*

    function(expr1, ...)	function call
    See below |functions|.

    lambda expression				*expr-lambda* *lambda*

    {args -> expr1}		legacy lambda expression		*E451*
    (args) => expr1		|Vim9| lambda expression

    A lambda expression creates a new unnamed function which returns the result of
    evaluating |expr1|.  Lambda expressions differ from |user-functions| in
    the following ways:

    1. The body of the lambda expression is an |expr1| and not a sequence of |Ex|
       commands.
    2. The prefix "a:" should not be used for arguments.  E.g.:
    	:let F = {arg1, arg2 -> arg1 - arg2}
    	:echo F(5, 2)
    	3

    The arguments are optional.  Example:
    	:let F = {-> 'error function'}
    	:echo F('ignored')
    	error function

    The |Vim9| lambda does not only use a different syntax, it also adds type
    checking and can be split over multiple lines, see |vim9-lambda|.

    							*closure*
    Lambda expressions can access outer scope variables and arguments.  This is
    often called a closure.  Example where "i" and "a:arg" are used in a lambda
    while they already exist in the function scope.  They remain valid even after
    the function returns:
    	:function Foo(arg)
    	:  let i = 3
    	:  return {x -> x + i - a:arg}
    	:endfunction
    	:let Bar = Foo(4)
    	:echo Bar(6)
    	5

    Note that the variables must exist in the outer scope before the lambda is
    defined for this to work.  See also |:func-closure|.

    Lambda and closure support can be checked with:
    	if has('lambda')

    Examples for using a lambda expression with |sort()|, |map()| and |filter()|:
    	:echo map([1, 2, 3], {idx, val -> val + 1})
    <	[2, 3, 4]
    	:echo sort([3,7,2,1,4], {a, b -> a - b})
    	[1, 2, 3, 4, 7]

    The lambda expression is also useful for Channel, Job and timer:
    	:let timer = timer_start(500,
    			\ {-> execute("echo 'Handler called'", "")},
    			\ {'repeat': 3})
    	Handler called
    	Handler called
    	Handler called

    Note that it is possible to cause memory to be used and not freed if the
    closure is referenced by the context it depends on:
    	function Function()
    	   let x = 0
    	   let F = {-> x}
    	 endfunction
    The closure uses "x" from the function scope, and "F" in that same scope
    refers to the closure.  This cycle results in the memory not being freed.
    Recommendation: don't do this.

    Notice how execute() is used to execute an Ex command.  That's ugly though.
    In Vim9 script you can use a command block, see |inline-function|.

    Although you can use the loop variable of a `for` command, it must still exist
    when the closure is called, otherwise you get an error.  *E1302*

    Lambda expressions have internal names like '<lambda>42'.  If you get an error
    for a lambda expression, you can find what it is with the following command:
    	:function <lambda>42
    See also: |numbered-function|

    3. Internal variable			*internal-variables* *E461* *E1001*

    An internal variable name can be made up of letters, digits and '_'.  But it
    cannot start with a digit.  In legacy script it is also possible to use curly
    braces, see |curly-braces-names|.

    In legacy script an internal variable is created with the ":let" command
    |:let|.  An internal variable is explicitly destroyed with the ":unlet"
    command |:unlet|.
    Using a name that is not an internal variable or refers to a variable that has
    been destroyed results in an error.

    In |Vim9| script `:let` is not used and variables work differently, see |:var|.

    						*variable-scope*
    There are several name spaces for variables.  Which one is to be used is
    specified by what is prepended:

    		(nothing) In a function: local to the function;
    			  in a legacy script: global;
    			  in a |Vim9|  script: local to the script
    |buffer-variable|    b:	  Local to the current buffer.
    |window-variable|    w:	  Local to the current window.
    |tabpage-variable|   t:	  Local to the current tab page.
    |global-variable|    g:	  Global.
    |local-variable|     l:	  Local to a function (only in a legacy function)
    |script-variable|    s:	  Local to a |:source|'ed Vim script.
    |function-argument|  a:	  Function argument (only in a legacy function).
    |vim-variable|       v:	  Global, predefined by Vim.

    The scope name by itself can be used as a |Dictionary|.  For example, to
    delete all script-local variables:
    	:for k in keys(s:)
    	:    unlet s:[k]
    	:endfor

    Note: in Vim9 script variables can also be local to a block of commands, see
    |vim9-scopes|.
    						*buffer-variable* *b:var* *b:*
    A variable name that is preceded with "b:" is local to the current buffer.
    Thus you can have several "b:foo" variables, one for each buffer.
    This kind of variable is deleted when the buffer is wiped out or deleted with
    |:bdelete|.

    One local buffer variable is predefined:
    					*b:changedtick* *changetick*
    b:changedtick	The total number of changes to the current buffer.  It is
    		incremented for each change.  An undo command is also a change
    		in this case.  Resetting 'modified' when writing the buffer is
    		also counted.
    		This can be used to perform an action only when the buffer has
    		changed.  Example:
    		    :if my_changedtick != b:changedtick
    		    :	let my_changedtick = b:changedtick
    		    :	call My_Update()
    		    :endif
    		You cannot change or delete the b:changedtick variable.
    		If you need more information about the change see
    		|listener_add()|.

    						*window-variable* *w:var* *w:*
    A variable name that is preceded with "w:" is local to the current window.  It
    is deleted when the window is closed.

    						*tabpage-variable* *t:var* *t:*
    A variable name that is preceded with "t:" is local to the current tab page,
    It is deleted when the tab page is closed. {not available when compiled
    without the |+windows| feature}

    						*global-variable* *g:var* *g:*
    Inside functions and in |Vim9| script global variables are accessed with "g:".
    Omitting this will access a variable local to a function or script.  "g:"
    can also be used in any other place if you like.

    						*local-variable* *l:var* *l:*
    Inside functions local variables are accessed without prepending anything.
    But you can also prepend "l:" if you like.  However, without prepending "l:"
    you may run into reserved variable names.  For example "count".  By itself it
    refers to "v:count".  Using "l:count" you can have a local variable with the
    same name.

    						*script-variable* *s:var*
    In a legacy Vim script variables starting with "s:" can be used.  They cannot
    be accessed from outside of the scripts, thus are local to the script.
    In |Vim9| script the "s:" prefix can be omitted, variables are script-local by
    default.

    They can be used in:
    - commands executed while the script is sourced
    - functions defined in the script
    - autocommands defined in the script
    - functions and autocommands defined in functions and autocommands which were
      defined in the script (recursively)
    - user defined commands defined in the script
    Thus not in:
    - other scripts sourced from this one
    - mappings
    - menus
    - etc.

    Script variables can be used to avoid conflicts with global variable names.
    Take this example:

    	let s:counter = 0
    	function MyCounter()
    	  let s:counter = s:counter + 1
    	  echo s:counter
    	endfunction
    	command Tick call MyCounter()

    You can now invoke "Tick" from any script, and the "s:counter" variable in
    that script will not be changed, only the "s:counter" in the script where
    "Tick" was defined is used.

    Another example that does the same:

    	let s:counter = 0
    	command Tick let s:counter = s:counter + 1 | echo s:counter

    When calling a function and invoking a user-defined command, the context for
    script variables is set to the script where the function or command was
    defined.

    The script variables are also available when a function is defined inside a
    function that is defined in a script.  Example:

    	let s:counter = 0
    	function StartCounting(incr)
    	  if a:incr
    	    function MyCounter()
    	      let s:counter = s:counter + 1
    	    endfunction
    	  else
    	    function MyCounter()
    	      let s:counter = s:counter - 1
    	    endfunction
    	  endif
    	endfunction

    This defines the MyCounter() function either for counting up or counting down
    when calling StartCounting().  It doesn't matter from where StartCounting() is
    called, the s:counter variable will be accessible in MyCounter().

    When the same script is sourced again it will use the same script variables.
    They will remain valid as long as Vim is running.  This can be used to
    maintain a counter:

    	if !exists("s:counter")
    	  let s:counter = 1
    	  echo "script executed for the first time"
    	else
    	  let s:counter = s:counter + 1
    	  echo "script executed " .. s:counter .. " times now"
    	endif

    Note that this means that filetype plugins don't get a different set of script
    variables for each buffer.  Use local buffer variables instead |b:var|.

    PREDEFINED VIM VARIABLES			*vim-variable* *v:var* *v:*
    							*E963* *E1063*
    Most variables are read-only, when a variable can be set by the user, it will
    be mentioned at the variable description below. The type cannot be changed.

    					*v:argv* *argv-variable*
    v:argv		The command line arguments Vim was invoked with.  This is a
    		list of strings.  The first item is the Vim command.
    		See |v:progpath| for the command with full path.

    					*v:beval_col* *beval_col-variable*
    v:beval_col	The number of the column, over which the mouse pointer is.
    		This is the byte index in the |v:beval_lnum| line.
    		Only valid while evaluating the 'balloonexpr' option.

    					*v:beval_bufnr* *beval_bufnr-variable*
    v:beval_bufnr	The number of the buffer, over which the mouse pointer is. Only
    		valid while evaluating the 'balloonexpr' option.

    					*v:beval_lnum* *beval_lnum-variable*
    v:beval_lnum	The number of the line, over which the mouse pointer is. Only
    		valid while evaluating the 'balloonexpr' option.

    					*v:beval_text* *beval_text-variable*
    v:beval_text	The text under or after the mouse pointer.  Usually a word as
    		it is useful for debugging a C program.  'iskeyword' applies,
    		but a dot and "->" before the position is included.  When on a
    		']' the text before it is used, including the matching '[' and
    		word before it.  When on a Visual area within one line the
    		highlighted text is used.  Also see |<cexpr>|.
    		Only valid while evaluating the 'balloonexpr' option.

    					*v:beval_winnr* *beval_winnr-variable*
    v:beval_winnr	The number of the window, over which the mouse pointer is. Only
    		valid while evaluating the 'balloonexpr' option.  The first
    		window has number zero (unlike most other places where a
    		window gets a number).

    					*v:beval_winid* *beval_winid-variable*
    v:beval_winid	The |window-ID| of the window, over which the mouse pointer
    		is.  Otherwise like v:beval_winnr.

    					*v:char* *char-variable*
    v:char		Argument for evaluating 'formatexpr' and used for the typed
    		character when using <expr> in an abbreviation |:map-<expr>|.
    		It is also used by the |InsertCharPre|, |InsertEnter|,
    		|KeyInputPre|, |CmdlineLeave| and |CmdlineLeavePre| events.

    			*v:charconvert_from* *charconvert_from-variable*
    v:charconvert_from
    		The name of the character encoding of a file to be converted.
    		Only valid while evaluating the 'charconvert' option.

    			*v:charconvert_to* *charconvert_to-variable*
    v:charconvert_to
    		The name of the character encoding of a file after conversion.
    		Only valid while evaluating the 'charconvert' option.

    					*v:clipmethod*
    v:clipmethod	The current method of accessing the clipboard that is being
    		used.  Can either have the value of:
    			wayland		The Wayland protocol is being used.
    			x11		X11 selections are being used.
    			gui		GUI specific method is being used
    			other		Some other method is being used
    			none		Clipboard functionality is disabled or
    					unavailable.
    		See 'clipmethod' for more details.

    					*v:cmdarg* *cmdarg-variable*
    v:cmdarg	This variable is used for two purposes:
    		1. The extra arguments given to a file read/write command.
    		   Currently these are "++enc=" and "++ff=".  This variable is
    		   set before an autocommand event for a file read/write
    		   command is triggered.  There is a leading space to make it
    		   possible to append this variable directly after the
    		   read/write command.  Note: The "+cmd" argument isn't
    		   included here, because it will be executed anyway.
    		2. When printing a PostScript file with ":hardcopy" this is
    		   the argument for the ":hardcopy" command.  This can be used
    		   in 'printexpr'.

    					*v:cmdbang* *cmdbang-variable*
    v:cmdbang	Set like v:cmdarg for a file read/write command.  When a "!"
    		was used the value is 1, otherwise it is 0.  Note that this
    		can only be used in autocommands.  For user commands |<bang>|
    		can be used.

    						*v:collate* *collate-variable*
    v:collate	The current locale setting for collation order of the runtime
    		environment.  This allows Vim scripts to be aware of the
    		current locale encoding.  Technical: it's the value of
    		LC_COLLATE.  When not using a locale the value is "C".
    		This variable can not be set directly, use the |:language|
    		command.
    		See |multi-lang|.

    								*v:colornames*
    v:colornames    A dictionary that maps color names to hex color strings. These
    		color names can be used with the |highlight-guifg|,
    		|highlight-guibg|, and |highlight-guisp| parameters.

    		The key values in the dictionary (the color names) should be
    		lower cased, because Vim looks up a color by its lower case
    		name.

    		Updating an entry in v:colornames has no immediate effect on
    		the syntax highlighting. The highlight commands (probably in a
    		colorscheme script) need to be re-evaluated in order to use
    		the updated color values. For example:

    		    :let v:colornames['fuscia'] = '#cf3ab4'
    		    :let v:colornames['mauve'] = '#915f6d'
    		    :highlight Normal guifg=fuscia guibg=mauve

    		This cannot be used to override the |cterm-colors| but it can
    		be used to override other colors. For example, the X11 colors
    		defined in the `colors/lists/default.vim` (previously defined
    		in |rgb|). When defining new color names in a plugin, the
    		recommended practice is to set a color entry only when it does
    		not already exist. For example:

    		    :call extend(v:colornames, {
    			\ 'fuscia': '#cf3ab4',
    			\ 'mauve': '#915f6d,
    			\ }, 'keep')

    		Using |extend()| with the 'keep' option updates each color only
    		if it did not exist in |v:colornames|. Doing so allows the
    		user to choose the precise color value for a common name
    		by setting it in their |.vimrc|.

    		It is possible to remove entries from this dictionary but
    		doing so is NOT recommended, because it is disruptive to
    		other scripts. It is also unlikely to achieve the desired
    		result because the |:colorscheme| and |:highlight| commands
    		will both automatically load all `colors/lists/default.vim`
    		color scripts.

    		You can make changes to that file, but make sure to add new
    		keys instead of updating existing ones, otherwise Vim will skip
    		loading the file (thinking it hasn't been changed).

    				*v:completed_item* *completed_item-variable*
    v:completed_item
    		|Dictionary| containing the |complete-items| for the most
    		recently completed word after |CompleteDone|.  The
    		|Dictionary| is empty if the completion failed.
    		Note: Plugins can modify the value to emulate the builtin
    		|CompleteDone| event behavior.

    					*v:count* *count-variable*
    v:count		The count given for the last Normal mode command.  Can be used
    		to get the count before a mapping.  Read-only.  Example:
    	:map _x :<C-U>echo "the count is " .. v:count<CR>
    		Note: The <C-U> is required to remove the line range that you
    		get when typing ':' after a count.
    		When there are two counts, as in "3d2w", they are multiplied,
    		just like what happens in the command, "d6w" for the example.
    		Also used for evaluating the 'formatexpr' option.
    		"count" also works, for backwards compatibility, unless
    		|scriptversion| is 3 or higher.

    					*v:count1* *count1-variable*
    v:count1	Just like "v:count", but defaults to one when no count is
    		used.

    						*v:ctype* *ctype-variable*
    v:ctype		The current locale setting for characters of the runtime
    		environment.  This allows Vim scripts to be aware of the
    		current locale encoding.  Technical: it's the value of
    		LC_CTYPE.  When not using a locale the value is "C".
    		This variable can not be set directly, use the |:language|
    		command.
    		See |multi-lang|.

    					*v:dying* *dying-variable*
    v:dying		Normally zero.  When a deadly signal is caught it's set to
    		one.  When multiple signals are caught the number increases.
    		Can be used in an autocommand to check if Vim didn't
    		terminate normally. {only works on Unix}
    		Example:
    	:au VimLeave * if v:dying | echo "\nAAAAaaaarrrggghhhh!!!\n" | endif
    		Note: if another deadly signal is caught when v:dying is one,
    		VimLeave autocommands will not be executed.

    					*v:exiting* *exiting-variable*
    v:exiting	Vim exit code.  Normally zero, non-zero when something went
    		wrong.  The value is v:null before invoking the |VimLeavePre|
    		and |VimLeave| autocmds.  See |:q|, |:x| and |:cquit|.
    		Example:
    			:au VimLeave * echo "Exit value is " .. v:exiting

    					*v:echospace* *echospace-variable*
    v:echospace	Number of screen cells that can be used for an `:echo` message
    		in the last screen line before causing the |hit-enter-prompt|.
    		Depends on 'showcmd', 'ruler' and 'columns'.  You need to
    		check 'cmdheight' for whether there are full-width lines
    		available above the last line.

    					*v:errmsg* *errmsg-variable*
    v:errmsg	Last given error message.  It's allowed to set this variable.
    		Example:
    	:let v:errmsg = ""
    	:silent! next
    	:if v:errmsg != ""
    	:  ... handle error
    		"errmsg" also works, for backwards compatibility, unless
    		|scriptversion| is 3 or higher.

    				*v:errors* *errors-variable* *assert-return*
    v:errors	Errors found by assert functions, such as |assert_true()|.
    		This is a list of strings.
    		The assert functions append an item when an assert fails.
    		The return value indicates this: a one is returned if an item
    		was added to v:errors, otherwise zero is returned.
    		To remove old results make it empty:
    	:let v:errors = []
    		If v:errors is set to anything but a list it is made an empty
    		list by the assert function.

    					*v:event* *event-variable*
    v:event		Dictionary containing information about the current
    		|autocommand|.  See the specific event for what it puts in
    		this dictionary.
    		The dictionary is emptied when the |autocommand| finishes,
    		please refer to |dict-identity| for how to get an independent
    		copy of it.  Use |deepcopy()| if you want to keep the
    		information after the event triggers.  Example:
    			au TextYankPost * let g:foo = deepcopy(v:event)

    					*v:exception* *exception-variable*
    v:exception	The value of the exception most recently caught and not
    		finished.  See also |v:stacktrace|, |v:throwpoint|, and
    		|throw-variables|.
    		Example:
    	:try
    	:  throw "oops"
    	:catch /.*/
    	:  echo "caught " .. v:exception
    	:endtry
    		Output: "caught oops".

    					*v:false* *false-variable*
    v:false		A Number with value zero. Used to put "false" in JSON.  See
    		|json_encode()|.
    		When used as a string this evaluates to "v:false".
    			echo v:false
    			v:false
    		That is so that eval() can parse the string back to the same
    		value.  Read-only.
    		In |Vim9| script "false" can be used which has a boolean type.

    					*v:fcs_reason* *fcs_reason-variable*
    v:fcs_reason	The reason why the |FileChangedShell| event was triggered.
    		Can be used in an autocommand to decide what to do and/or what
    		to set v:fcs_choice to.  Possible values:
    			deleted		file no longer exists
    			conflict	file contents, mode or timestamp was
    					changed and buffer is modified
    			changed		file contents has changed
    			mode		mode of file changed
    			time		only file timestamp changed

    					*v:fcs_choice* *fcs_choice-variable*
    v:fcs_choice	What should happen after a |FileChangedShell| event was
    		triggered.  Can be used in an autocommand to tell Vim what to
    		do with the affected buffer:
    			reload		Reload the buffer (does not work if
    					the file was deleted).
    			edit		Reload the buffer and detect the
    					values for options such as
    					'fileformat', 'fileencoding', 'binary'
    					(does not work if the file was
    					deleted).
    			ask		Ask the user what to do, as if there
    					was no autocommand.  Except that when
    					only the timestamp changed nothing
    					will happen.
    			<empty>		Nothing, the autocommand should do
    					everything that needs to be done.
    		The default is empty.  If another (invalid) value is used then
    		Vim behaves like it is empty, there is no warning message.

    					*v:fname* *fname-variable*
    v:fname		When evaluating 'includeexpr': the file name that was
    		detected.  Empty otherwise.

    					*v:fname_in* *fname_in-variable*
    v:fname_in	The name of the input file.  Valid while evaluating:
    			option		used for
    			'charconvert'	file to be converted
    			'diffexpr'	original file
    			'patchexpr'	original file
    			'printexpr'	file to be printed
    		And set to the swap file name for |SwapExists|.

    					*v:fname_out* *fname_out-variable*
    v:fname_out	The name of the output file.  Only valid while
    		evaluating:
    			option		used for
    			'charconvert'	resulting converted file (*)
    			'diffexpr'	output of diff
    			'patchexpr'	resulting patched file
    		(*) When doing conversion for a write command (e.g., ":w
    		file") it will be equal to v:fname_in.  When doing conversion
    		for a read command (e.g., ":e file") it will be a temporary
    		file and different from v:fname_in.

    					*v:fname_new* *fname_new-variable*
    v:fname_new	The name of the new version of the file.  Only valid while
    		evaluating 'diffexpr'.

    					*v:fname_diff* *fname_diff-variable*
    v:fname_diff	The name of the diff (patch) file.  Only valid while
    		evaluating 'patchexpr'.

    					*v:folddashes* *folddashes-variable*
    v:folddashes	Used for 'foldtext': dashes representing foldlevel of a closed
    		fold.
    		Read-only in the |sandbox|. |fold-foldtext|

    					*v:foldlevel* *foldlevel-variable*
    v:foldlevel	Used for 'foldtext': foldlevel of closed fold.
    		Read-only in the |sandbox|. |fold-foldtext|

    					*v:foldend* *foldend-variable*
    v:foldend	Used for 'foldtext': last line of closed fold.
    		Read-only in the |sandbox|. |fold-foldtext|

    					*v:foldstart* *foldstart-variable*
    v:foldstart	Used for 'foldtext': first line of closed fold.
    		Read-only in the |sandbox|. |fold-foldtext|

    					*v:hlsearch* *hlsearch-variable*
    v:hlsearch	Variable that indicates whether search highlighting is on.
    		Setting it makes sense only if 'hlsearch' is enabled which
    		requires |+extra_search|. Setting this variable to zero acts
    		like the |:nohlsearch| command, setting it to one acts like
    			let &hlsearch = &hlsearch
    		Note that the value is restored when returning from a
    		function. |function-search-undo|.

    					*v:insertmode* *insertmode-variable*
    v:insertmode	Used for the |InsertEnter| and |InsertChange| autocommand
    		events.  Values:
    			i	Insert mode
    			r	Replace mode
    			v	Virtual Replace mode

    						*v:key* *key-variable*
    v:key		Key of the current item of a |Dictionary|.  Only valid while
    		evaluating the expression used with |map()| and |filter()|.
    		Read-only.

    						*v:lang* *lang-variable*
    v:lang		The current locale setting for messages of the runtime
    		environment.  This allows Vim scripts to be aware of the
    		current language.  Technical: it's the value of LC_MESSAGES.
    		The value is system dependent.
    		This variable can not be set directly, use the |:language|
    		command.
    		It can be different from |v:ctype| when messages are desired
    		in a different language than what is used for character
    		encoding.  See |multi-lang|.

    						*v:lc_time* *lc_time-variable*
    v:lc_time	The current locale setting for time messages of the runtime
    		environment.  This allows Vim scripts to be aware of the
    		current language.  Technical: it's the value of LC_TIME.
    		This variable can not be set directly, use the |:language|
    		command.  See |multi-lang|.

    						*v:lnum* *lnum-variable*
    v:lnum		Line number for the 'foldexpr' |fold-expr|, 'formatexpr' and
    		'indentexpr' expressions, tab page number for 'guitablabel'
    		and 'guitabtooltip'.  Only valid while one of these
    		expressions is being evaluated.  Read-only when in the
    		|sandbox|.

    						*v:maxcol* *maxcol-variable*
    v:maxcol	Maximum line length.  Depending on where it is used it can be
    		screen columns, characters or bytes.  The value currently is
    		2147483647 on all systems.

    					*v:mouse_win* *mouse_win-variable*
    v:mouse_win	Window number for a mouse click obtained with |getchar()|.
    		First window has number 1, like with |winnr()|.  The value is
    		zero when there was no mouse button click.

    					*v:mouse_winid* *mouse_winid-variable*
    v:mouse_winid	Window ID for a mouse click obtained with |getchar()|.
    		The value is zero when there was no mouse button click.

    					*v:mouse_lnum* *mouse_lnum-variable*
    v:mouse_lnum	Line number for a mouse click obtained with |getchar()|.
    		This is the text line number, not the screen line number.  The
    		value is zero when there was no mouse button click.

    					*v:mouse_col* *mouse_col-variable*
    v:mouse_col	Column number for a mouse click obtained with |getchar()|.
    		This is the screen column number, like with |virtcol()|.  The
    		value is zero when there was no mouse button click.

    					*v:none* *none-variable* *None*
    v:none		An empty String. Used to put an empty item in JSON.  See
    		|json_encode()|.
    		This can also be used as a function argument to use the
    		default value, see |none-function_argument|.
    		When used as a number this evaluates to zero.
    		When used as a string this evaluates to "v:none".
    			echo v:none
    			v:none
    		That is so that eval() can parse the string back to the same
    		value.  Read-only.
    		Note that using `== v:none` and `!= v:none`  will often give
    		an error.  Instead, use `is v:none` and `isnot v:none` .

    					*v:null* *null-variable*
    v:null		An empty String. Used to put "null" in JSON.  See
    		|json_encode()|.
    		When used as a number this evaluates to zero.
    		When used as a string this evaluates to "v:null".
    			echo v:null
    			v:null
    		That is so that eval() can parse the string back to the same
    		value.  Read-only.
    		In |Vim9| script `null` can be used without "v:".
    		In some places `v:null` and `null` can be used for a List,
    		Dict, Job, etc. that is not set.  That is slightly different
    		than an empty List, Dict, etc.

    					*v:numbermax* *numbermax-variable*
    v:numbermax	Maximum value of a number.

    					*v:numbermin* *numbermin-variable*
    v:numbermin	Minimum value of a number (negative).

    					*v:numbersize* *numbersize-variable*
    v:numbersize	Number of bits in a Number.  This is normally 64, but on some
    		systems it may be 32.

    					*v:oldfiles* *oldfiles-variable*
    v:oldfiles	List of file names that is loaded from the |viminfo| file on
    		startup.  These are the files that Vim remembers marks for.
    		The length of the List is limited by the ' argument of the
    		'viminfo' option (default is 100).
    		When the |viminfo| file is not used the List is empty.
    		Also see |:oldfiles| and |c_#<|.
    		The List can be modified, but this has no effect on what is
    		stored in the |viminfo| file later.  If you use values other
    		than String this will cause trouble.
    		{only when compiled with the |+viminfo| feature}

    						    *v:option_new*
    v:option_new    New value of the option. Valid while executing an |OptionSet|
    		autocommand.
    						    *v:option_old*
    v:option_old    Old value of the option. Valid while executing an |OptionSet|
    		autocommand. Depending on the command used for setting and the
    		kind of option this is either the local old value or the
    		global old value.
    						    *v:option_oldlocal*
    v:option_oldlocal
    		Old local value of the option. Valid while executing an
    		|OptionSet| autocommand.
    						    *v:option_oldglobal*
    v:option_oldglobal
    		Old global value of the option. Valid while executing an
    		|OptionSet| autocommand.
    						    *v:option_type*
    v:option_type   Scope of the set command. Valid while executing an
    		|OptionSet| autocommand. Can be either "global" or "local"
    						    *v:option_command*
    v:option_command
    		Command used to set the option. Valid while executing an
    		|OptionSet| autocommand.
    			value		option was set via
    			"setlocal"	|:setlocal| or ":let l:xxx"
    			"setglobal"	|:setglobal| or ":let g:xxx"
    			"set"		|:set| or |:let|
    			"modeline"	|modeline|
    					*v:operator* *operator-variable*
    v:operator	The last operator given in Normal mode.  This is a single
    		character except for commands starting with <g> or <z>,
    		in which case it is two characters.  Best used alongside
    		|v:prevcount| and |v:register|.  Useful if you want to cancel
    		Operator-pending mode and then use the operator, e.g.:
    			:omap O <Esc>:call MyMotion(v:operator)<CR>
    		The value remains set until another operator is entered, thus
    		don't expect it to be empty.
    		v:operator is not set for |:delete|, |:yank| or other Ex
    		commands.
    		Read-only.

    					*v:prevcount* *prevcount-variable*
    v:prevcount	The count given for the last but one Normal mode command.
    		This is the v:count value of the previous command.  Useful if
    		you want to cancel Visual or Operator-pending mode and then
    		use the count, e.g.:
    			:vmap % <Esc>:call MyFilter(v:prevcount)<CR>
    		Read-only.

    					*v:profiling* *profiling-variable*
    v:profiling	Normally zero.  Set to one after using ":profile start".
    		See |profiling|.

    					*v:progname* *progname-variable*
    v:progname	Contains the name (with path removed) with which Vim was
    		invoked.  Allows you to do special initialisations for |view|,
    		|evim| etc., or any other name you might symlink to Vim.
    		Read-only.

    					*v:progpath* *progpath-variable*
    v:progpath	Contains the command with which Vim was invoked, in a form
    		that when passed to the shell will run the same Vim executable
    		as the current one (if $PATH remains unchanged).
    		Useful if you want to message a Vim server using a
    		|--remote-expr|.
    		To get the full path use:
    			echo exepath(v:progpath)
    		If the command has a relative path it will be expanded to the
    		full path, so that it still works after `:cd`. Thus starting
    		"./vim" results in "/home/user/path/to/vim/src/vim".
    		On Linux and other systems it will always be the full path.
    		On Mac it may just be "vim" and using exepath() as mentioned
    		above should be used to get the full path.
    		On MS-Windows the executable may be called "vim.exe", but the
    		".exe" is not added to v:progpath.
    		Read-only.

    				*v:python3_version* *python3-version-variable*
    v:python3_version
    		Version of Python 3 that Vim was built against.  When
    		Python is loaded dynamically (|python-dynamic|), this version
    		should exactly match the Python library up to the minor
    		version (e.g.  3.10.2 and 3.10.3 are compatible as the minor
    		version is "10", whereas 3.9.4 and 3.10.3 are not compatible).
    		When |python-stable-abi| is used, this will be the minimum
    		Python version that you can use instead. (e.g. if
    		v:python3_version indicates 3.9, you can use 3.9, 3.10, or
    		anything above).

    		This number is encoded as a hex number following Python ABI
    		versioning conventions.  Do the following to have a
    		human-readable full version in hex:
    			echo printf("%08X", v:python3_version)
    <		You can obtain only the minor version by doing:
    			echo and(v:python3_version>>16,0xff)
    		Read-only.

    					*v:register* *register-variable*
    v:register	The name of the register in effect for the current normal mode
    		command (regardless of whether that command actually used a
    		register).  Or for the currently executing normal mode mapping
    		(use this in custom commands that take a register).
    		If none is supplied it is the default register '"', unless
    		'clipboard' contains "unnamed" or "unnamedplus", then it is
    		'*' or '+'.
    		Also see |getreg()| and |setreg()|

    					*v:scrollstart* *scrollstart-variable*
    v:scrollstart	String describing the script or function that caused the
    		screen to scroll up.  It's only set when it is empty, thus the
    		first reason is remembered.  It is set to "Unknown" for a
    		typed command.
    		This can be used to find out why your script causes the
    		hit-enter prompt.

    					*v:servername* *servername-variable*
    v:servername	The resulting registered |client-server-name| if any.
    		Read-only.

    v:searchforward			*v:searchforward* *searchforward-variable*
    		Search direction:  1 after a forward search, 0 after a
    		backward search.  It is reset to forward when directly setting
    		the last search pattern, see |quote/|.
    		Note that the value is restored when returning from a
    		function. |function-search-undo|.
    		Read-write.

    					*v:shell_error* *shell_error-variable*
    v:shell_error	Result of the last shell command.  When non-zero, the last
    		shell command had an error.  When zero, there was no problem.
    		This only works when the shell returns the error code to Vim.
    		The value -1 is often used when the command could not be
    		executed.  Read-only.
    		Example:
    	:!mv foo bar
    	:if v:shell_error
    	:  echo 'could not rename "foo" to "bar"!'
    	:endif
    		"shell_error" also works, for backwards compatibility, unless
    		|scriptversion| is 3 or higher.

    					*v:sizeofint* *sizeofint-variable*
    v:sizeofint	Number of bytes in an int.  Depends on how Vim was compiled.
    		This is only useful for deciding whether a test will give the
    		expected result.

    					*v:sizeoflong* *sizeoflong-variable*
    v:sizeoflong	Number of bytes in a long.  Depends on how Vim was compiled.
    		This is only useful for deciding whether a test will give the
    		expected result.

    				*v:sizeofpointer* *sizeofpointer-variable*
    v:sizeofpointer	Number of bytes in a pointer.  Depends on how Vim was compiled.
    		This is only useful for deciding whether a test will give the
    		expected result.

    					*v:stacktrace* *stacktrace-variable*
    v:stacktrace	The stack trace of the exception most recently caught and
    		not finished.  Refer to |getstacktrace()| for the structure of
    		stack trace.  See also |v:exception|, |v:throwpoint|, and
    		|throw-variables|.

    					*v:statusmsg* *statusmsg-variable*
    v:statusmsg	Last given status message.  It's allowed to set this variable.

    					*v:swapname* *swapname-variable*
    v:swapname	Only valid when executing |SwapExists| autocommands: Name of
    		the swap file found.  Read-only.

    					*v:swapchoice* *swapchoice-variable*
    v:swapchoice	|SwapExists| autocommands can set this to the selected choice
    		for handling an existing swap file:
    			'o'	Open read-only
    			'e'	Edit anyway
    			'r'	Recover
    			'd'	Delete swapfile
    			'q'	Quit
    			'a'	Abort
    		The value should be a single-character string.  An empty value
    		results in the user being asked, as would happen when there is
    		no SwapExists autocommand.  The default is empty.

    					*v:swapcommand* *swapcommand-variable*
    v:swapcommand	Normal mode command to be executed after a file has been
    		opened.  Can be used for a |SwapExists| autocommand to have
    		another Vim open the file and jump to the right place.  For
    		example, when jumping to a tag the value is ":tag tagname\r".
    		For ":edit +cmd file" the value is ":cmd\r".

    				*v:t_TYPE* *v:t_bool* *t_bool-variable*
    v:t_bool	Value of |Boolean| type.  Read-only.  See: |type()|
    					*v:t_channel* *t_channel-variable*
    v:t_channel	Value of |Channel| type.  Read-only.  See: |type()|
    					*v:t_dict* *t_dict-variable*
    v:t_dict	Value of |Dictionary| type.  Read-only.  See: |type()|
    					*v:t_float* *t_float-variable*
    v:t_float	Value of |Float| type.  Read-only.  See: |type()|
    					*v:t_func* *t_func-variable*
    v:t_func	Value of |Funcref| type.  Read-only.  See: |type()|
    					*v:t_job* *t_job-variable*
    v:t_job		Value of |Job| type.  Read-only.  See: |type()|
    					*v:t_list* *t_list-variable*
    v:t_list	Value of |List| type.  Read-only.  See: |type()|
    					*v:t_none* *t_none-variable*
    v:t_none	Value of |None| type.  Read-only.  See: |type()|
    					*v:t_number* *t_number-variable*
    v:t_number	Value of |Number| type.  Read-only.  See: |type()|
    					*v:t_string* *t_string-variable*
    v:t_string	Value of |String| type.  Read-only.  See: |type()|
    					*v:t_blob* *t_blob-variable*
    v:t_blob	Value of |Blob| type.  Read-only.  See: |type()|
    					*v:t_class* *t_class-variable*
    v:t_class	Value of |class| type.  Read-only.  See: |type()|
    					*v:t_object* *t_object-variable*
    v:t_object	Value of |object| type.  Read-only.  See: |type()|
    					*v:t_typealias* *t_typealias-variable*
    v:t_typealias	Value of |typealias| type.  Read-only.  See: |type()|
    					*v:t_enum* *t_enum-variable*
    v:t_enum	Value of |enum| type.  Read-only.  See: |type()|
    					*v:t_enumvalue* *t_enumvalue-variable*
    v:t_enumvalue	Value of |enumvalue| type.  Read-only.  See: |type()|
    					*v:t_tuple* *t_tuple-variable*
    v:t_tuple	Value of |Tuple| type.  Read-only.  See: |type()|

    				    *v:termresponse* *termresponse-variable*
    v:termresponse	The escape sequence returned by the terminal for the |t_RV|
    		termcap entry.  It is set when Vim receives an escape sequence
    		that starts with ESC [ or CSI, then '>' or '?' and ends in a
    		'c', with only digits and ';' in between.
    		When this variable is set, the TermResponse autocommand event
    		is fired, so that you can react to the response from the
    		terminal.  The TermResponseAll event is also fired, with
    		<amatch> set to "version".  You can use |terminalprops()| to
    		see what Vim figured out about the terminal.
    		The response from a new xterm is: "<Esc>[> Pp ; Pv ; Pc c".  Pp
    		is the terminal type: 0 for vt100 and 1 for vt220.  Pv is the
    		patch level (since this was introduced in patch 95, it's
    		always 95 or higher).  Pc is always zero.
    		If Pv is 141 or higher then Vim will try to request terminal
    		codes.  This only works with xterm |xterm-codes|.
    		{only when compiled with |+termresponse| feature}

    				    *v:termblinkresp* *termblinkresp-variable*
    v:termblinkresp	The escape sequence returned by the terminal for the |t_RC|
    		termcap entry.  This is used to find out whether the terminal
    		cursor is blinking. This is used by |term_getcursor()|.  When
    		this variable is set, the TermResponseAll autocommand event is
    		fired, with <amatch> set to "cursorblink".

    				    *v:termstyleresp* *termstyleresp-variable*
    v:termstyleresp	The escape sequence returned by the terminal for the |t_RS|
    		termcap entry.  This is used to find out what the shape of the
    		cursor is.  This is used by |term_getcursor()|.  When this
    		variable is set, the TermResponseAll autocommand event is
    		fired, with <amatch> set to "cursorshape".

    					*v:termrbgresp* *termrbgresp-variable*
    v:termrbgresp	The escape sequence returned by the terminal for the |t_RB|
    		termcap entry.  This is used to find out what the terminal
    		background color is; see 'background'.  When this variable is
    		set, the TermResponseAll autocommand event is fired, with
    		<amatch> set to "background".

    					*v:termrfgresp* *termrfgresp-variable*
    v:termrfgresp	The escape sequence returned by the terminal for the |t_RF|
    		termcap entry.  This is used to find out what the terminal
    		foreground color is.  When this variable is set, the
    		TermResponseAll autocommand event is fired, with <amatch> set
    		to "foreground".

    					*v:termu7resp* *termu7resp-variable*
    v:termu7resp	The escape sequence returned by the terminal for the |t_u7|
    		termcap entry.  This is used to find out what the terminal
    		does with ambiguous width characters, see 'ambiwidth'.  When
    		this variable is set, the TermResponseAll autocommand event is
    		fired, with <amatch> set to "ambiguouswidth".

    					*v:termda1* *termda1-variable*
    v:termda1	The escape sequence returned by a primary device attributes
    		(DA1) query from the terminal.  When this variable is set, the
    		TermResponseAll autocommand event is fired, with <amatch> set
    		to "da1".  Can be used to detect OSC 52 support in a terminal.

    					*v:termosc* *termosc-variable*
    v:termosc	The escape sequence of the most recent OSC response received
    		from the terminal.  When this variable is set, the
    		|TermResponseAll| autocommand event is fired, with <amatch>
    		set to "osc".

    					*v:testing* *testing-variable*
    v:testing	Must be set before using `test_garbagecollect_now()`.
    		Also, when set certain error messages won't be shown for 2
    		seconds. (e.g. "'dictionary' option is empty")

    				*v:this_session* *this_session-variable*
    v:this_session	Full filename of the last loaded or saved session file.  See
    		|:mksession|.  It is allowed to set this variable.  When no
    		session file has been saved, this variable is empty.
    		"this_session" also works, for backwards compatibility, unless
    		|scriptversion| is 3 or higher

    					*v:throwpoint* *throwpoint-variable*
    v:throwpoint	The point where the exception most recently caught and not
    		finished was thrown.  Not set when commands are typed.  See
    		also |v:exception|, |v:stacktrace|, and |throw-variables|.
    		Example:
    	:try
    	:  throw "oops"
    	:catch /.*/
    	:  echo "Exception from" v:throwpoint
    	:endtry
    		Output: "Exception from test.vim, line 2"

    						*v:true* *true-variable*
    v:true		A Number with value one. Used to put "true" in JSON.  See
    		|json_encode()|.
    		When used as a string this evaluates to "v:true".
    			echo v:true
    			v:true
    		That is so that eval() can parse the string back to the same
    		value.  Read-only.
    		In |Vim9| script "true" can be used which has a boolean type.
    						*v:val* *val-variable*
    v:val		Value of the current item of a |List| or |Dictionary|.  Only
    		valid while evaluating the expression used with |map()| and
    		|filter()|.  Read-only.

    					*v:version* *version-variable*
    v:version	Version number of Vim: Major version number times 100 plus
    		minor version number.  Version 5.0 is 500.  Version 5.1
    		is 501.  Read-only.  "version" also works, for backwards
    		compatibility, unless |scriptversion| is 3 or higher.
    		Use |has()| to check if a certain patch was included, e.g.:
    			if has("patch-7.4.123")
    		Note that patch numbers are specific to the version, thus both
    		version 5.0 and 5.1 may have a patch 123, but these are
    		completely different.

    					*v:versionlong* *versionlong-variable*
    v:versionlong	Like v:version, but also including the patchlevel in the last
    		four digits.  Version 8.1 with patch 123 has value 8010123.
    		This can be used like this:
    			if v:versionlong >= 8010123
    		However, if there are gaps in the list of patches included
    		this will not work well.  This can happen if a recent patch
    		was included into an older version, e.g. for a security fix.
    		Use the has() function to make sure the patch is actually
    		included.

    				*v:vim_did_enter* *vim_did_enter-variable*
    v:vim_did_enter	Zero until most of startup is done.  It is set to one just
    		before |VimEnter| autocommands are triggered.

    					*v:warningmsg* *warningmsg-variable*
    v:warningmsg	Last given warning message.  It's allowed to set this variable.

    				*v:wayland_display* *wayland_display-variable*
    v:wayland_display
    		The name of the Wayland display that Vim is connected to.
    		Equivalent to the $WAYLAND_DISPLAY environment variable.
    		If this is empty, then Vim is not connected to any display.

    					*v:windowid* *windowid-variable*
    v:windowid	When any X11/Wayland based GUI is running or when running in a
    		terminal and Vim connects to the X server (|-X|) this will be
    		set to the window ID.
    		When an MS-Windows GUI is running this will be set to the
    		window handle.
    		Otherwise the value is zero.
    		Note: for windows inside Vim use |winnr()| or |win_getid()|,
    		see |window-ID|.

    4. Builtin Functions					*functions*

    See |function-list| for a list grouped by what the function is used for.

    The alphabetic list of all builtin functions and details are in a separate
    help file: |builtin-functions|.

    5. Defining functions					*user-functions*

    New functions can be defined.  These can be called just like builtin
    functions.  The function takes arguments, executes a sequence of Ex commands
    and can return a value.

    You can find most information about defining functions in |userfunc|.
    For Vim9 functions, which execute much faster, support type checking and more,
    see |vim9|.

    6. Curly braces names					*curly-braces-names*

    In most places where you can use a variable, you can use a "curly braces name"
    variable.  This is a regular variable name with one or more expressions
    wrapped in braces {} like this:
    	my_{adjective}_variable

    This only works in legacy Vim script, not in |Vim9| script.

    When Vim encounters this, it evaluates the expression inside the braces, puts
    that in place of the expression, and re-interprets the whole as a variable
    name.  So in the above example, if the variable "adjective" was set to
    "noisy", then the reference would be to "my_noisy_variable", whereas if
    "adjective" was set to "quiet", then it would be to "my_quiet_variable".

    One application for this is to create a set of variables governed by an option
    value.  For example, the statement
    	echo my_{&background}_message

    would output the contents of "my_dark_message" or "my_light_message" depending
    on the current value of 'background'.

    You can use multiple brace pairs:
    	echo my_{adverb}_{adjective}_message
    ..or even nest them:
    	echo my_{ad{end_of_word}}_message
    where "end_of_word" is either "verb" or "jective".

    However, the expression inside the braces must evaluate to a valid single
    variable name, e.g. this is invalid:
    	:let foo='a + b'
    	:echo c{foo}d
    .. since the result of expansion is "ca + bd", which is not a variable name.

    						*curly-braces-function-names*
    You can call and define functions by an evaluated name in a similar way.
    Example:
    	:let func_end='whizz'
    	:call my_func_{func_end}(parameter)

    This would call the function "my_func_whizz(parameter)".

    This does NOT work:
      :let i = 3
      :let @{i} = ''  " error
      :echo @{i}      " error

    7. Commands						*expression-commands*

    Note: in |Vim9| script `:let` is not used.  `:var` is used for variable
    declarations and assignments do not use a command.  |vim9-declaration|

    :let {var-name} = {expr1}				*:let* *E18*
    			Set internal variable {var-name} to the result of the
    			expression {expr1}.  The variable will get the type
    			from the {expr}.  If {var-name} didn't exist yet, it
    			is created.

    :let {var-name}[{idx}] = {expr1}			*E689* *E1141*
    			Set a list item to the result of the expression
    			{expr1}.  {var-name} must refer to a list and {idx}
    			must be a valid index in that list.  For nested list
    			the index can be repeated.
    			This cannot be used to add an item to a |List|.
    			This cannot be used to set a byte in a String.  You
    			can do that like this:
    				:let var = var[0:2] .. 'X' .. var[4:]
    			When {var-name} is a |Blob| then {idx} can be the
    			length of the blob, in which case one byte is
    			appended.

    					*E711* *E719* *E1165* *E1166* *E1183*
    :let {var-name}[{idx1}:{idx2}] = {expr1}		*E708* *E709* *E710*
    			Set a sequence of items in a |List| to the result of
    			the expression {expr1}, which must be a list with the
    			correct number of items.
    			{idx1} can be omitted, zero is used instead.
    			{idx2} can be omitted, meaning the end of the list.
    			When the selected range of items is partly past the
    			end of the list, items will be added.

    			*:let+=* *:let-=* *:letstar=* *:let/=*  *:let%=*
    			*:let.=* *:let..=* *E734* *E985* *E1019*
    :let {var} += {expr1}	Like ":let {var} = {var} + {expr1}".
    :let {var} -= {expr1}	Like ":let {var} = {var} - {expr1}".
    :let {var} *= {expr1}	Like ":let {var} = {var} * {expr1}".
    :let {var} /= {expr1}	Like ":let {var} = {var} / {expr1}".
    :let {var} %= {expr1}	Like ":let {var} = {var} % {expr1}".
    :let {var} .= {expr1}	Like ":let {var} = {var} . {expr1}".
    :let {var} ..= {expr1}	Like ":let {var} = {var} .. {expr1}".
    			These fail if {var} was not set yet and when the type
    			of {var} and {expr1} don't fit the operator.
    			`+=` modifies a |List| or a |Blob| in-place instead of
    			creating a new one.
    			`.=` is not supported with Vim script version 2 and
    			later, see |vimscript-version|.

    :let ${env-name} = {expr1}			*:let-environment* *:let-$*
    			Set environment variable {env-name} to the result of
    			the expression {expr1}.  The type is always String.

    			On some systems making an environment variable empty
    			causes it to be deleted.  Many systems do not make a
    			difference between an environment variable that is not
    			set and an environment variable that is empty.

    :let ${env-name} .= {expr1}
    :let ${env-name} ..= {expr1}
    			Append {expr1} to the environment variable {env-name}.
    			If the environment variable didn't exist yet this
    			works like "=".
    			`.=` is not supported with Vim script version 2 and
    			later, see |vimscript-version|.

    :let @{reg-name} = {expr1}			*:let-register* *:let-@*
    			Write the result of the expression {expr1} in register
    			{reg-name}.  {reg-name} must be a single letter, and
    			must be the name of a writable register (see
    			|registers|).  "@@" can be used for the unnamed
    			register, "@/" for the search pattern.
    			If the result of {expr1} ends in a <CR> or <NL>, the
    			register will be linewise, otherwise it will be set to
    			characterwise.
    			This can be used to clear the last search pattern:
    				:let @/ = ""
    			This is different from searching for an empty string,
    			that would match everywhere.

    :let @{reg-name} .= {expr1}
    :let @{reg-name} ..= {expr1}
    			Append {expr1} to register {reg-name}.  If the
    			register was empty it's like setting it to {expr1}.
    			`.=` is not supported with Vim script version 2 and
    			later, see |vimscript-version|.

    :let &{option-name} = {expr1}			*:let-option* *:let-&*
    			Set option {option-name} to the result of the
    			expression {expr1}.  A String or Number value is
    			always converted to the type of the option.
    			For an option local to a window or buffer the effect
    			is just like using the |:set| command: both the local
    			value and the global value are changed.
    			Example:
    				:let &path = &path .. ',/usr/local/include'
    			This also works for terminal codes in the form t_xx.
    			But only for alphanumerical names.  Example:
    				:let &t_k1 = "\<Esc>[234;"
    			When the code does not exist yet it will be created as
    			a terminal key code, there is no error.

    :let &{option-name} .= {expr1}
    :let &{option-name} ..= {expr1}
    			For a string option: Append {expr1} to the value.
    			Does not insert a comma like |:set+=|.
    			`.=` is not supported with Vim script version 2 and
    			later, see |vimscript-version|.

    :let &{option-name} += {expr1}
    :let &{option-name} -= {expr1}
    			For a number or boolean option: Add or subtract
    			{expr1}.

    :let &l:{option-name} = {expr1}
    :let &l:{option-name} += {expr1}
    :let &l:{option-name} -= {expr1}
    :let &l:{option-name} .= {expr1}
    :let &l:{option-name} ..= {expr1}
    			Like above, but only set the local value of an option
    			(if there is one).  Works like |:setlocal|.
    			`.=` is not supported with Vim script version 2 and
    			later, see |vimscript-version|.

    :let &g:{option-name} = {expr1}
    :let &g:{option-name} += {expr1}
    :let &g:{option-name} -= {expr1}
    :let &g:{option-name} .= {expr1}
    :let &g:{option-name} ..= {expr1}
    			Like above, but only set the global value of an option
    			(if there is one).  Works like |:setglobal|.
    			`.=` is not supported with Vim script version 2 and
    			later, see |vimscript-version|.

    						*E1093* *E1537* *E1538* *E1535*
    :let [{name1}, {name2}, ...] = {expr1}		*:let-unpack* *E687* *E688*
    			{expr1} must evaluate to a |List| or a |Tuple|.  The
    			first item in the list or tuple is assigned to
    			{name1}, the second item to {name2}, etc.
    			The number of names must match the number of items in
    			the |List| or |Tuple|.
    			Each name can be one of the items of the ":let"
    			command as mentioned above.
    			Example:
    				:let [s, item] = GetItem(s)
    			Detail: {expr1} is evaluated first, then the
    			assignments are done in sequence.  This matters if
    			{name2} depends on {name1}.  Example:
    				:let x = [0, 1]
    				:let i = 0
    				:let [i, x[i]] = [1, 2]
    				:echo x
    			The result is [0, 2].

    :let [{name1}, {name2}, ...] += {expr1}
    :let [{name1}, {name2}, ...] -= {expr1}
    :let [{name1}, {name2}, ...] *= {expr1}
    :let [{name1}, {name2}, ...] /= {expr1}
    :let [{name1}, {name2}, ...] %= {expr1}
    :let [{name1}, {name2}, ...] .= {expr1}
    :let [{name1}, {name2}, ...] ..= {expr1}
    			Like above, but add, subtract, multiply, divide,
    			modulo, or append the value for each |List| or |Tuple|
    			item.
    			`.=` is not supported with Vim script version 2 and
    			later, see |vimscript-version|.

    :let [{name}, ..., ; {lastname}] = {expr1}				*E452*
    			Like |:let-unpack| above, but the |List| or |Tuple|
    			may have more items than there are names.  A list or a
    			tuple of the remaining items is assigned to
    			{lastname}.  If there are no remaining items,
    			{lastname} is set to an empty list or tuple.
    			Example:
    				:let [a, b; rest] = ["aval", "bval", 3, 4]
    				:let [a, b; rest] = ("aval", "bval", 3, 4)

    :let [{name}, ..., ; {lastname}] += {expr1}
    :let [{name}, ..., ; {lastname}] -= {expr1}
    :let [{name}, ..., ; {lastname}] .= {expr1}
    :let [{name}, ..., ; {lastname}] ..= {expr1}
    			Like above, but add/subtract/append the value for each
    			|List| item.
    			`.=` is not supported with Vim script version 2 and
    			later, see |vimscript-version|.

    						*:let=<<* *:let-heredoc*
    					*E990* *E991* *E172* *E221* *E1145*
    :let {var-name} =<< [trim] [eval] {endmarker}
    text...
    text...
    {endmarker}
    			Set internal variable {var-name} to a |List|
    			containing the lines of text bounded by the string
    			{endmarker}.

    			If "eval" is not specified, then each line of text is
    			used as a |literal-string|, except that single quotes
    			does not need to be doubled.
    			If "eval" is specified, then any Vim expression in the
    			form {expr} is evaluated and the result replaces the
    			expression, like with |interpolated-string|.
    			Example where $HOME is expanded:
    				let lines =<< trim eval END
    				  some text
    				  See the file {$HOME}/.vimrc
    				  more text
    				END
    			There can be multiple Vim expressions in a single line
    			but an expression cannot span multiple lines.  If any
    			expression evaluation fails, then the assignment fails.

    			{endmarker} must not contain white space.
    			{endmarker} cannot start with a lower case character.
    			The last line should end only with the {endmarker}
    			string without any other character.  Watch out for
    			white space after {endmarker}!

    			Without "trim" any white space characters in the lines
    			of text are preserved.  If "trim" is specified before
    			{endmarker}, then indentation is stripped so you can
    			do:
    				let text =<< trim END
    				   if ok
    				     echo 'done'
    				   endif
    				END
    			Results in: ["if ok", "  echo 'done'", "endif"]
    			The marker must line up with "let" and the indentation
    			of the first line is removed from all the text lines.
    			Specifically: all the leading indentation exactly
    			matching the leading indentation of the first
    			non-empty text line is stripped from the input lines.
    			All leading indentation exactly matching the leading
    			indentation before `let` is stripped from the line
    			containing {endmarker}.  Note that the difference
    			between space and tab matters here.

    			If {var-name} didn't exist yet, it is created.
    			Cannot be followed by another command, but can be
    			followed by a comment.

    			To avoid line continuation to be applied, consider
    			adding 'C' to 'cpoptions':
    				set cpo+=C
    				let var =<< END
    				   \ leading backslash
    				END
    				set cpo-=C

    			Examples:
    				let var1 =<< END
    				Sample text 1
    				    Sample text 2
    				Sample text 3
    				END

    				let data =<< trim DATA
    					1 2 3 4
    					5 6 7 8
    				DATA

    				let code =<< trim eval CODE
    				   let v = {10 + 20}
    				   let h = "{$HOME}"
    				   let s = "{Str1()} abc {Str2()}"
    				   let n = {MyFunc(3, 4)}
    				CODE

    								*E121*
    :let {var-name}	...	List the value of variable {var-name}.  Multiple
    			variable names may be given.  Special names recognized
    			here:				*E738*
    			  g:	global variables
    			  b:	local buffer variables
    			  w:	local window variables
    			  t:	local tab page variables
    			  s:	script-local variables
    			  l:	local function variables
    			  v:	Vim variables.
    			This does not work in Vim9 script. |vim9-declaration|

    :let			List the values of all variables.  The type of the
    			variable is indicated before the value:
    			    <nothing>	String
    				#	Number
    				*	Funcref
    			This does not work in Vim9 script. |vim9-declaration|

    :unl[et][!] {name} ...			*:unlet* *:unl* *E108* *E795* *E1081*
    			Remove the internal variable {name}.  Several variable
    			names can be given, they are all removed.  The name
    			may also be a |List| or |Dictionary| item.
    			With [!] no error message is given for non-existing
    			variables.
    			One or more items from a |List| can be removed:
    				:unlet list[3]	  " remove fourth item
    				:unlet list[3:]   " remove fourth item to last
    			One item from a |Dictionary| can be removed at a time:

    				:unlet dict['two']
    				:unlet dict.two
    			This is especially useful to clean up used global
    			variables and script-local variables (these are not
    			deleted when the script ends).  Function-local
    			variables are automatically deleted when the function
    			ends.
    			In |Vim9| script variables declared in a function or
    			script cannot be removed.

    :unl[et] ${env-name} ...			*:unlet-environment* *:unlet-$*
    			Remove environment variable {env-name}.
    			Can mix {name} and ${env-name} in one :unlet command.
    			No error message is given for a non-existing
    			variable, also without !.
    			If the system does not support deleting an environment
    			variable, it is made empty.

    						*:cons* *:const* *E1018*
    :cons[t] {var-name} = {expr1}
    :cons[t] [{name1}, {name2}, ...] = {expr1}
    :cons[t] [{name}, ..., ; {lastname}] = {expr1}
    :cons[t] {var-name} =<< [trim] [eval] {marker}
    text...
    text...
    {marker}
    			Similar to |:let|, but additionally lock the variable
    			after setting the value.  This is the same as locking
    			the variable with |:lockvar| just after |:let|, thus:
    				:const x = 1
    <			is equivalent to:
    				:let x = 1
    				:lockvar! x
    			NOTE: in Vim9 script `:const` works differently, see
    			|vim9-const|
    			This is useful if you want to make sure the variable
    			is not modified.  If the value is a List or Dictionary
    			literal then the items also cannot be changed:
    				const ll = [1, 2, 3]
    				let ll[1] = 5  " Error!
    <			Nested references are not locked:
    				let lvar = ['a']
    				const lconst = [0, lvar]
    				let lconst[0] = 2  " Error!
    				let lconst[1][0] = 'b'  " OK
    							*E995*
    			It is an error to specify an existing variable with
    			|:const|.
    				:let x = 1
    				:const x = 1  " Error!
    							*E996*
    			Note that environment variables, option values and
    			register values cannot be used here, since they cannot
    			be locked.

    :cons[t]
    :cons[t] {var-name}
    			If no argument is given or only {var-name} is given,
    			the behavior is the same as |:let|.

    :lockv[ar][!] [depth] {name} ...			*:lockvar* *:lockv*
    			Lock the internal variable {name}.  Locking means that
    			it can no longer be changed (until it is unlocked).
    			A locked variable can be deleted:
    				:lockvar v
    				:let v = 'asdf'	  " fails!
    				:unlet v	  " works
    			*E741* *E940* *E1118* *E1119* *E1120* *E1121* *E1122*
    			If you try to change a locked variable you get an
    			error message: "E741: Value is locked: {name}".
    			If you try to lock or unlock a built-in variable you
    			get an error message: "E940: Cannot lock or unlock
    			variable {name}".

    			[depth] is relevant when locking a |List|, a |Tuple|
    			or a |Dictionary|.  It specifies how deep the locking
    			goes:
    				0	Lock the variable {name} but not its
    					value.
    				1	Lock the |List| or |Tuple| or
    					|Dictionary| itself, cannot add or
    					remove items, but can still change
    					their values.
    				2	Also lock the values, cannot change
    					the items.  If an item is a |List| or
    					|Tuple| or |Dictionary|, cannot add or
    					remove items, but can still change the
    					values.
    				3	Like 2 but for the |List| / |Tuple| /
    					|Dictionary| in the |List| / |Tuple| /
    					|Dictionary|, one level deeper.
    			The default [depth] is 2, thus when {name} is a
    			|List|, a |Tuple| or a |Dictionary| the values cannot
    			be changed.

    			Example with [depth] 0:
    				let mylist = [1, 2, 3]
    				lockvar 0 mylist
    				let mylist[0] = 77	" OK
    				call add(mylist, 4)	" OK
    				let mylist = [7, 8, 9]  " Error!
    								*E743*
    			For unlimited depth use [!] and omit [depth].
    			However, there is a maximum depth of 100 to catch
    			loops.

    			Note that when two variables refer to the same |List|
    			and you lock one of them, the |List| will also be
    			locked when used through the other variable.
    			Example:
    				:let l = [0, 1, 2, 3]
    				:let cl = l
    				:lockvar l
    				:let cl[1] = 99		" won't work!
    			You may want to make a copy of a list to avoid this.
    			See |deepcopy()|.

    							*E1391* *E1392*
    			Locking and unlocking object and class variables is
    			currently NOT supported.

    :unlo[ckvar][!] [depth] {name} ...		*:unlockvar* *:unlo* *E1246*
    			Unlock the internal variable {name}.  Does the
    			opposite of |:lockvar|.

    			If {name} does not exist:
    			- In |Vim9| script an error is given.
    			- In legacy script this is silently ignored.

    :if {expr1}		    *:if* *:end* *:endif* *:en* *E171* *E579* *E580*
    :en[dif]		Execute the commands until the next matching `:else`
    			or `:endif` if {expr1} evaluates to non-zero.
    			Although the short forms work, it is recommended to
    			always use `:endif` to avoid confusion and to make
    			auto-indenting work properly.

    			From Vim version 4.5 until 5.0, every Ex command in
    			between the `:if` and `:endif` is ignored.  These two
    			commands were just to allow for future expansions in a
    			backward compatible way.  Nesting was allowed.  Note
    			that any `:else` or `:elseif` was ignored, the `else`
    			part was not executed either.

    			You can use this to remain compatible with older
    			versions:
    				:if version >= 500
    				:  version-5-specific-commands
    				:endif
    			The commands still need to be parsed to find the
    			`endif`.  Sometimes an older Vim has a problem with a
    			new command.  For example, `:silent` is recognized as
    			a `:substitute` command.  In that case `:execute` can
    			avoid problems:
    				:if version >= 600
    				:  execute "silent 1,$delete"
    				:endif

    			In |Vim9| script `:endif` cannot be shortened, to
    			improve script readability.
    			NOTE: The `:append` and `:insert` commands don't work
    			properly in between `:if` and `:endif`.

    						*:else* *:el* *E581* *E583*
    :el[se]			Execute the commands until the next matching `:else`
    			or `:endif` if they previously were not being
    			executed.
    			In |Vim9| script `:else` cannot be shortened, to
    			improve script readability.

    					*:elseif* *:elsei* *E582* *E584*
    :elsei[f] {expr1}	Short for `:else` `:if`, with the addition that there
    			is no extra `:endif`.
    			In |Vim9| script `:elseif` cannot be shortened, to
    			improve script readability.

    :wh[ile] {expr1}			*:while* *:endwhile* *:wh* *:endw*
    						*E170* *E585* *E588* *E733*
    :endw[hile]		Repeat the commands between `:while` and `:endwhile`,
    			as long as {expr1} evaluates to non-zero.
    			When an error is detected from a command inside the
    			loop, execution continues after the `endwhile`.
    			Example:
    				:let lnum = 1
    				:while lnum <= line("$")
    				   :call FixLine(lnum)
    				   :let lnum = lnum + 1
    				:endwhile

    			In |Vim9| script `:while`  and `:endwhile` cannot be
    			shortened, to improve script readability.
    			NOTE: The `:append` and `:insert` commands don't work
    			properly inside a `:while` and `:for` loop.

    :for {var} in {object}					*:for* *E690* *E732*
    :endfo[r]						*:endfo* *:endfor*
    			Repeat the commands between `:for` and `:endfor` for
    			each item in {object}.  {object} can be a |List|,
    			a |Tuple|, a |Blob| or a |String|. *E1177*

    			Variable {var} is set to the value of each item.
    			In |Vim9| script the loop variable must not have been
    			declared yet, unless when it is a
    			global/window/tab/buffer variable.

    			When an error is detected for a command inside the
    			loop, execution continues after the `endfor`.
    			Changing {object} inside the loop affects what items
    			are used.  Make a copy if this is unwanted:
    				:for item in copy(mylist)

    			When {object} is a |List| and not making a copy, in
    			legacy script Vim stores a reference to the next item
    			in the |List| before executing the commands with the
    			current item.  Thus the current item can be removed
    			without effect.  Removing any later item means it will
    			not be found.  Thus the following example works (an
    			inefficient way to make a |List| empty):
    				for item in mylist
    				   call remove(mylist, 0)
    				endfor
    			Note that reordering the |List| (e.g., with sort() or
    			reverse()) may have unexpected effects.
    			In |Vim9| script the index is used.  If an item before
    			the current one is deleted the next item will be
    			skipped.

    			When {object} is a |Blob|, Vim always makes a copy to
    			iterate over.  Unlike with |List|, modifying the
    			|Blob| does not affect the iteration.

    			When {object} is a |String| each item is a string with
    			one character, plus any combining characters.

    			In |Vim9| script `:endfor` cannot be shortened, to
    			improve script readability.

    :for [{var1}, {var2}, ...] in {listlist}
    :endfo[r]							*E1140*
    			Like `:for` above, but each item in {listlist} must be
    			a list, of which each item is assigned to {var1},
    			{var2}, etc.  Example:
    				:for [lnum, col] in [[1, 3], [2, 5], [3, 8]]
    				   :echo getline(lnum)[col]
    				:endfor

    						*:continue* *:con* *E586*
    :con[tinue]		When used inside a `:while` or `:for` loop, jumps back
    			to the start of the loop.
    			If it is used after a `:try` inside the loop but
    			before the matching `:finally` (if present), the
    			commands following the `:finally` up to the matching
    			`:endtry` are executed first.  This process applies to
    			all nested `:try`s inside the loop.  The outermost
    			`:endtry` then jumps back to the start of the loop.

    			In |Vim9| script `:cont` is the shortest form, to
    			improve script readability.
    						*:break* *:brea* *E587*
    :brea[k]		When used inside a `:while` or `:for` loop, skips to
    			the command after the matching `:endwhile` or
    			`:endfor`.
    			If it is used after a `:try` inside the loop but
    			before the matching `:finally` (if present), the
    			commands following the `:finally` up to the matching
    			`:endtry` are executed first.  This process applies to
    			all nested `:try`s inside the loop.  The outermost
    			`:endtry` then jumps to the command after the loop.

    			In |Vim9| script `:break` cannot be shortened, to
    			improve script readability.

    :try						*:try* *:endt* *:endtry*
    						*E600* *E601* *E602* *E1032*
    :endt[ry]		Change the error handling for the commands between
    			`:try` and `:endtry` including everything being
    			executed across `:source` commands, function calls,
    			or autocommand invocations.

    			When an error or interrupt is detected and there is
    			a `:finally` command following, execution continues
    			after the `:finally`.  Otherwise, or when the
    			`:endtry` is reached thereafter, the next
    			(dynamically) surrounding `:try` is checked for
    			a corresponding `:finally` etc.  Then the script
    			processing is terminated.  Whether a function
    			definition has an "abort" argument does not matter.
    			Example:
    		try | call Unknown() | finally | echomsg "cleanup" | endtry
    		echomsg "not reached"

    			Moreover, an error or interrupt (dynamically) inside
    			`:try` and `:endtry` is converted to an exception.  It
    			can be caught as if it were thrown by a `:throw`
    			command (see `:catch`).  In this case, the script
    			processing is not terminated.

    			The value "Vim:Interrupt" is used for an interrupt
    			exception.  An error in a Vim command is converted
    			to a value of the form "Vim({command}):{errmsg}",
    			other errors are converted to a value of the form
    			"Vim:{errmsg}".  {command} is the full command name,
    			and {errmsg} is the message that is displayed if the
    			error exception is not caught, always beginning with
    			the error number.
    			Examples:
    		try | sleep 100 | catch /^Vim:Interrupt$/ | endtry
    		try | edit | catch /^Vim(edit):E\d\+/ | echo "error" | endtry

    			In |Vim9| script `:endtry` cannot be shortened, to
    			improve script readability.

    					*:cat* *:catch*
    					*E603* *E604* *E605* *E654* *E1033*
    :cat[ch] /{pattern}/	The following commands until the next `:catch`,
    			`:finally`, or `:endtry` that belongs to the same
    			`:try` as the `:catch` are executed when an exception
    			matching {pattern} is being thrown and has not yet
    			been caught by a previous `:catch`.  Otherwise, these
    			commands are skipped.
    			When {pattern} is omitted all errors are caught.
    			Examples:
    		:catch /^Vim:Interrupt$/	 " catch interrupts (CTRL-C)
    		:catch /^Vim\%((\a\+)\)\=:E/	 " catch all Vim errors
    		:catch /^Vim\%((\a\+)\)\=:/	 " catch errors and interrupts
    		:catch /^Vim(write):/		 " catch all errors in :write
    		:catch /^Vim\%((\a\+)\)\=:E123:/ " catch error E123
    		:catch /my-exception/		 " catch user exception
    		:catch /.*/			 " catch everything
    		:catch				 " same as /.*/

    			Another character can be used instead of / around the
    			{pattern}, so long as it does not have a special
    			meaning (e.g., '|' or '"') and doesn't occur inside
    			{pattern}. *E1067*
    			Information about the exception is available in
    			|v:exception|.  Also see |throw-variables|.
    			NOTE: It is not reliable to ":catch" the TEXT of
    			an error message because it may vary in different
    			locales.
    			In |Vim9| script `:catch` cannot be shortened, to
    			improve script readability.

    					*:fina* *:finally* *E606* *E607*
    :fina[lly]		The following commands until the matching `:endtry`
    			are executed whenever the part between the matching
    			`:try` and the `:finally` is left:  either by falling
    			through to the `:finally` or by a `:continue`,
    			`:break`, `:finish`, or `:return`, or by an error or
    			interrupt or exception (see `:throw`).

    			In |Vim9| script `:finally` cannot be shortened, to
    			improve script readability and avoid confusion with
    			`:final`.

    						*:th* *:throw* *E608* *E1129*
    :th[row] {expr1}	The {expr1} is evaluated and thrown as an exception.
    			If the ":throw" is used after a `:try` but before the
    			first corresponding `:catch`, commands are skipped
    			until the first `:catch` matching {expr1} is reached.
    			If there is no such `:catch` or if the ":throw" is
    			used after a `:catch` but before the `:finally`, the
    			commands following the `:finally` (if present) up to
    			the matching `:endtry` are executed.  If the `:throw`
    			is after the `:finally`, commands up to the `:endtry`
    			are skipped.  At the ":endtry", this process applies
    			again for the next dynamically surrounding `:try`
    			(which may be found in a calling function or sourcing
    			script), until a matching `:catch` has been found.
    			If the exception is not caught, the command processing
    			is terminated.
    			Example:
    		:try | throw "oops" | catch /^oo/ | echo "caught" | endtry
    			Note that "catch" may need to be on a separate line
    			for when an error causes the parsing to skip the whole
    			line and not see the "|" that separates the commands.

    			In |Vim9| script `:throw` cannot be shortened, to
    			improve script readability.

    							*:ec* *:echo*
    :ec[ho] {expr1} ...	Echoes each {expr1}, with a space in between.  The
    			first {expr1} starts on a new line.
    			Also see |:comment|.
    			Use "\n" to start a new line.  Use "\r" to move the
    			cursor to the first column.
    			Uses the highlighting set by the `:echohl` command.
    			Cannot be followed by a comment.
    			Example:
    		:echo "the value of 'shell' is" &shell
    							*:echo-redraw*
    			A later redraw may make the message disappear again.
    			And since Vim mostly postpones redrawing until it's
    			finished with a sequence of commands this happens
    			quite often.  To avoid that a command from before the
    			`:echo` causes a redraw afterwards (redraws are often
    			postponed until you type something), force a redraw
    			with the `:redraw` command.  Example:
    		:new | redraw | echo "there is a new window"

    							*:echon*
    :echon {expr1} ...	Echoes each {expr1}, without anything added.  Also see
    			|:comment|.
    			Uses the highlighting set by the `:echohl` command.
    			Cannot be followed by a comment.
    			Example:
    				:echon "the value of 'shell' is " &shell

    			Note the difference between using `:echo`, which is a
    			Vim command, and `:!echo`, which is an external shell
    			command:
    		:!echo %		--> filename
    <			The arguments of ":!" are expanded, see |:_%|.
    		:!echo "%"		--> filename or "filename"
    			Like the previous example.  Whether you see the double
    			quotes or not depends on your 'shell'.
    		:echo %			--> nothing
    <			The '%' is an illegal character in an expression.
    		:echo "%"		--> %
    <			This just echoes the '%' character.
    		:echo expand("%")	--> filename
    			This calls the expand() function to expand the '%'.

    							*:echoh* *:echohl*
    :echoh[l] {name}	Use the highlight group {name} for the following
    			`:echo`, `:echon` and `:echomsg` commands.  Also used
    			for the `input()` prompt.  Example:
    		:echohl WarningMsg | echo "Don't panic!" | echohl None
    			Don't forget to set the group back to "None",
    			otherwise all following echo's will be highlighted.

    							*:echom* *:echomsg*
    :echom[sg] {expr1} ...	Echo the expression(s) as a true message, saving the
    			message in the |message-history|.
    			Spaces are placed between the arguments as with the
    			`:echo` command.  But unprintable characters are
    			displayed, not interpreted.
    			The parsing works slightly different from `:echo`,
    			more like `:execute`.  All the expressions are first
    			evaluated and concatenated before echoing anything.
    			If expressions does not evaluate to a Number or
    			String, string() is used to turn it into a string.
    			Uses the highlighting set by the `:echohl` command.
    			Example:
    		:echomsg "It's a Zizzer Zazzer Zuzz, as you can plainly see."
    			See |:echo-redraw| to avoid the message disappearing
    			when the screen is redrawn.

    					*:echow* *:echowin* *:echowindow*
    :[N]echow[indow] {expr1} ..
    			Like |:echomsg| but when the messages popup window is
    			available the message is displayed there.  This means
    			it will show for three seconds and avoid a
    			|hit-enter| prompt.  If you want to hide it before
    			that, press Esc in Normal mode (when it would
    			otherwise beep).  If it disappears too soon you can
    			use `:messages` to see the text.
    			When [N] is given then the window will show up for
    			this number of seconds.  The last `:echowindow` with a
    			count matters, it is used once only.
    			The message window is available when Vim was compiled
    			with the +timer and the +popupwin features.

    							*:echoe* *:echoerr*
    :echoe[rr] {expr1} ...	Echo the expression(s) as an error message, saving the
    			message in the |message-history|.  When used in a
    			script or function the line number will be added.
    			Spaces are placed between the arguments as with the
    			`:echomsg` command.  When used inside a try
    			conditional, the message is raised as an error
    			exception instead
    			(see |try-echoerr|).
    			Example:
    		:echoerr "This script just failed!"
    			If you just want a highlighted message use `:echohl`.
    			And to get a beep:
    		:exe "normal \<Esc>"

    :echoc[onsole] {expr1} ...				*:echoc* *:echoconsole*
    			Intended for testing: works like `:echomsg` but when
    			running in the GUI and started from a terminal write
    			the text to stdout.

    							*:eval*
    :eval {expr}		Evaluate {expr} and discard the result.  Example:
    				:eval Getlist()->Filter()->append('$')

    			The expression is supposed to have a side effect,
    			since the resulting value is not used.  In the example
    			the `append()` call appends the List with text to the
    			buffer.  This is similar to `:call` but works with any
    			expression.
    			In |Vim9| script an expression without an effect will
    			result in error *E1207* .  This should help noticing
    			mistakes.

    			The command can be shortened to `:ev` or `:eva`, but
    			these are hard to recognize and therefore not to be
    			used.

    			The command cannot be followed by "|" and another
    			command, since "|" is seen as part of the expression.

    							*:exe* *:execute*
    :exe[cute] {expr1} ...	Executes the string that results from the evaluation
    			of {expr1} as an Ex command.
    			Multiple arguments are concatenated, with a space in
    			between.  To avoid the extra space use the ".."
    			operator to concatenate strings into one argument.
    			{expr1} is used as the processed command, command line
    			editing keys are not recognized.
    			Cannot be followed by a comment.
    			Examples:
    		:execute "buffer" nextbuf
    		:execute "normal" count .. "w"

    			":execute" can be used to append a command to commands
    			that don't accept a '|'.  Example:
    		:execute '!ls' | echo "theend"

    			":execute" is also a nice way to avoid having to type
    			control characters in a Vim script for a ":normal"
    			command:
    		:execute "normal ixxx\<Esc>"
    			This has an <Esc> character, see |expr-string|.

    			Be careful to correctly escape special characters in
    			file names.  The |fnameescape()| function can be used
    			for Vim commands, |shellescape()| for |:!| commands.
    			Examples:
    		:execute "e " .. fnameescape(filename)
    		:execute "!ls " .. shellescape(filename, 1)

    			Note: The executed string may be any command-line, but
    			starting or ending "if", "while" and "for" does not
    			always work, because when commands are skipped the
    			":execute" is not evaluated and Vim loses track of
    			where blocks start and end.  Also "break" and
    			"continue" should not be inside ":execute".
    			This example does not work, because the ":execute" is
    			not evaluated and Vim does not see the "while", and
    			gives an error for finding an ":endwhile":
    		:if 0
    		: execute 'while i > 5'
    		:  echo "test"
    		: endwhile
    		:endif

    			It is allowed to have a "while" or "if" command
    			completely in the executed string:
    		:execute 'while i < 5 | echo i | let i = i + 1 | endwhile'

    							*:exe-comment*
    			":execute", ":echo" and ":echon" cannot be followed by
    			a comment directly, because they see the '"' as the
    			start of a string.  But, you can use '|' followed by a
    			comment.  Example:
    		:echo "foo" | "this is a comment

    8. Exception handling					*exception-handling*

    The Vim script language comprises an exception handling feature.  This section
    explains how it can be used in a Vim script.

    Exceptions may be raised by Vim on an error or on interrupt, see
    |catch-errors| and |catch-interrupt|.  You can also explicitly throw an
    exception by using the ":throw" command, see |throw-catch|.

    TRY CONDITIONALS					*try-conditionals*

    Exceptions can be caught or can cause cleanup code to be executed.  You can
    use a try conditional to specify catch clauses (that catch exceptions) and/or
    a finally clause (to be executed for cleanup).
       A try conditional begins with a |:try| command and ends at the matching
    |:endtry| command.  In between, you can use a |:catch| command to start
    a catch clause, or a |:finally| command to start a finally clause.  There may
    be none or multiple catch clauses, but there is at most one finally clause,
    which must not be followed by any catch clauses.  The lines before the catch
    clauses and the finally clause is called a try block.

         :try
         :	...
         :	...				TRY BLOCK
         :	...
         :catch /{pattern}/
         :	...
         :	...				CATCH CLAUSE
         :	...
         :catch /{pattern}/
         :	...
         :	...				CATCH CLAUSE
         :	...
         :finally
         :	...
         :	...				FINALLY CLAUSE
         :	...
         :endtry

    The try conditional allows to watch code for exceptions and to take the
    appropriate actions.  Exceptions from the try block may be caught.  Exceptions
    from the try block and also the catch clauses may cause cleanup actions.
       When no exception is thrown during execution of the try block, the control
    is transferred to the finally clause, if present.  After its execution, the
    script continues with the line following the ":endtry".
       When an exception occurs during execution of the try block, the remaining
    lines in the try block are skipped.  The exception is matched against the
    patterns specified as arguments to the ":catch" commands.  The catch clause
    after the first matching ":catch" is taken, other catch clauses are not
    executed.  The catch clause ends when the next ":catch", ":finally", or
    ":endtry" command is reached - whatever is first.  Then, the finally clause
    (if present) is executed.  When the ":endtry" is reached, the script execution
    continues in the following line as usual.
       When an exception that does not match any of the patterns specified by the
    ":catch" commands is thrown in the try block, the exception is not caught by
    that try conditional and none of the catch clauses is executed.  Only the
    finally clause, if present, is taken.  The exception pends during execution of
    the finally clause.  It is resumed at the ":endtry", so that commands after
    the ":endtry" are not executed and the exception might be caught elsewhere,
    see |try-nesting|.
       When during execution of a catch clause another exception is thrown, the
    remaining lines in that catch clause are not executed.  The new exception is
    not matched against the patterns in any of the ":catch" commands of the same
    try conditional and none of its catch clauses is taken.  If there is, however,
    a finally clause, it is executed, and the exception pends during its
    execution.  The commands following the ":endtry" are not executed.  The new
    exception might, however, be caught elsewhere, see |try-nesting|.
       When during execution of the finally clause (if present) an exception is
    thrown, the remaining lines in the finally clause are skipped.  If the finally
    clause has been taken because of an exception from the try block or one of the
    catch clauses, the original (pending) exception is discarded.  The commands
    following the ":endtry" are not executed, and the exception from the finally
    clause is propagated and can be caught elsewhere, see |try-nesting|.

    The finally clause is also executed, when a ":break" or ":continue" for
    a ":while" loop enclosing the complete try conditional is executed from the
    try block or a catch clause.  Or when a ":return" or ":finish" is executed
    from the try block or a catch clause of a try conditional in a function or
    sourced script, respectively.  The ":break", ":continue", ":return", or
    ":finish" pends during execution of the finally clause and is resumed when the
    ":endtry" is reached.  It is, however, discarded when an exception is thrown
    from the finally clause.
       When a ":break" or ":continue" for a ":while" loop enclosing the complete
    try conditional or when a ":return" or ":finish" is encountered in the finally
    clause, the rest of the finally clause is skipped, and the ":break",
    ":continue", ":return" or ":finish" is executed as usual.  If the finally
    clause has been taken because of an exception or an earlier ":break",
    ":continue", ":return", or ":finish" from the try block or a catch clause,
    this pending exception or command is discarded.

    For examples see |throw-catch| and |try-finally|.

    NESTING OF TRY CONDITIONALS				*try-nesting*

    Try conditionals can be nested arbitrarily.  That is, a complete try
    conditional can be put into the try block, a catch clause, or the finally
    clause of another try conditional.  If the inner try conditional does not
    catch an exception thrown in its try block or throws a new exception from one
    of its catch clauses or its finally clause, the outer try conditional is
    checked according to the rules above.  If the inner try conditional is in the
    try block of the outer try conditional, its catch clauses are checked, but
    otherwise only the finally clause is executed.  It does not matter for
    nesting, whether the inner try conditional is directly contained in the outer
    one, or whether the outer one sources a script or calls a function containing
    the inner try conditional.

    When none of the active try conditionals catches an exception, just their
    finally clauses are executed.  Thereafter, the script processing terminates.
    An error message is displayed in case of an uncaught exception explicitly
    thrown by a ":throw" command.  For uncaught error and interrupt exceptions
    implicitly raised by Vim, the error message(s) or interrupt message are shown
    as usual.

    For examples see |throw-catch|.

    EXAMINING EXCEPTION HANDLING CODE			*except-examine*

    Exception handling code can get tricky.  If you are in doubt what happens, set
    'verbose' to 13 or use the ":13verbose" command modifier when sourcing your
    script file.  Then you see when an exception is thrown, discarded, caught, or
    finished.  When using a verbosity level of at least 14, things pending in
    a finally clause are also shown.  This information is also given in debug mode
    (see |debug-scripts|).

    THROWING AND CATCHING EXCEPTIONS			*throw-catch*

    You can throw any number or string as an exception.  Use the |:throw| command
    and pass the value to be thrown as argument:
    	:throw 4711
    	:throw "string"
    							*throw-expression*
    You can also specify an expression argument.  The expression is then evaluated
    first, and the result is thrown:
    	:throw 4705 + strlen("string")
    	:throw strpart("strings", 0, 6)

    An exception might be thrown during evaluation of the argument of the ":throw"
    command.  Unless it is caught there, the expression evaluation is abandoned.
    The ":throw" command then does not throw a new exception.
       Example:

    	:function! Foo(arg)
    	:  try
    	:    throw a:arg
    	:  catch /foo/
    	:  endtry
    	:  return 1
    	:endfunction
    	:
    	:function! Bar()
    	:  echo "in Bar"
    	:  return 4710
    	:endfunction
    	:
    	:throw Foo("arrgh") + Bar()

    This throws "arrgh", and "in Bar" is not displayed since Bar() is not
    executed.
    	:throw Foo("foo") + Bar()
    however displays "in Bar" and throws 4711.

    Any other command that takes an expression as argument might also be
    abandoned by an (uncaught) exception during the expression evaluation.  The
    exception is then propagated to the caller of the command.
       Example:

    	:if Foo("arrgh")
    	:  echo "then"
    	:else
    	:  echo "else"
    	:endif

    Here neither of "then" or "else" is displayed.

    							*catch-order*
    Exceptions can be caught by a try conditional with one or more |:catch|
    commands, see |try-conditionals|.   The values to be caught by each ":catch"
    command can be specified as a pattern argument.  The subsequent catch clause
    gets executed when a matching exception is caught.
       Example:

    	:function! Foo(value)
    	:  try
    	:    throw a:value
    	:  catch /^\d\+$/
    	:    echo "Number thrown"
    	:  catch /.*/
    	:    echo "String thrown"
    	:  endtry
    	:endfunction
    	:
    	:call Foo(0x1267)
    	:call Foo('string')

    The first call to Foo() displays "Number thrown", the second "String thrown".
    An exception is matched against the ":catch" commands in the order they are
    specified.  Only the first match counts.  So you should place the more
    specific ":catch" first.  The following order does not make sense:

    	:  catch /.*/
    	:    echo "String thrown"
    	:  catch /^\d\+$/
    	:    echo "Number thrown"

    The first ":catch" here matches always, so that the second catch clause is
    never taken.

    							*throw-variables*
    If you catch an exception by a general pattern, you may access the exact value
    in the variable |v:exception|:

    	:  catch /^\d\+$/
    	:    echo "Number thrown.  Value is" v:exception

    You may also be interested where an exception was thrown.  This is stored in
    |v:throwpoint|.  And you can obtain the stack trace from |v:stacktrace|.
    Note that "v:exception", "v:stacktrace" and "v:throwpoint" are valid for the
    exception most recently caught as long it is not finished.
       Example:

    	:function! Caught()
    	:  if v:exception != ""
    	:    echo 'Caught "' .. v:exception .. '" in ' .. v:throwpoint
    	:  else
    	:    echo 'Nothing caught'
    	:  endif
    	:endfunction
    	:
    	:function! Foo()
    	:  try
    	:    try
    	:      try
    	:	 throw 4711
    	:      finally
    	:	 call Caught()
    	:      endtry
    	:    catch /.*/
    	:      call Caught()
    	:      throw "oops"
    	:    endtry
    	:  catch /.*/
    	:    call Caught()
    	:  finally
    	:    call Caught()
    	:  endtry
    	:endfunction
    	:
    	:call Foo()

    This displays

    	Nothing caught
    	Caught "4711" in function Foo, line 4
    	Caught "oops" in function Foo, line 10
    	Nothing caught

    A practical example:  The following command ":LineNumber" displays the line
    number in the script or function where it has been used:

    	:function! LineNumber()
    	:    return substitute(v:throwpoint, '.*\D\(\d\+\).*', '\1', "")
    	:endfunction
    	:command! LineNumber try | throw "" | catch | echo LineNumber() | endtry

    							*try-nested*
    An exception that is not caught by a try conditional can be caught by
    a surrounding try conditional:

    	:try
    	:  try
    	:    throw "foo"
    	:  catch /foobar/
    	:    echo "foobar"
    	:  finally
    	:    echo "inner finally"
    	:  endtry
    	:catch /foo/
    	:  echo "foo"
    	:endtry

    The inner try conditional does not catch the exception, just its finally
    clause is executed.  The exception is then caught by the outer try
    conditional.  The example displays "inner finally" and then "foo".

    							*throw-from-catch*
    You can catch an exception and throw a new one to be caught elsewhere from the
    catch clause:

    	:function! Foo()
    	:  throw "foo"
    	:endfunction
    	:
    	:function! Bar()
    	:  try
    	:    call Foo()
    	:  catch /foo/
    	:    echo "Caught foo, throw bar"
    	:    throw "bar"
    	:  endtry
    	:endfunction
    	:
    	:try
    	:  call Bar()
    	:catch /.*/
    	:  echo "Caught" v:exception
    	:endtry

    This displays "Caught foo, throw bar" and then "Caught bar".

    							*rethrow*
    There is no real rethrow in the Vim script language, but you may throw
    "v:exception" instead:

    	:function! Bar()
    	:  try
    	:    call Foo()
    	:  catch /.*/
    	:    echo "Rethrow" v:exception
    	:    throw v:exception
    	:  endtry
    	:endfunction
    							*try-echoerr*
    Note that this method cannot be used to "rethrow" Vim error or interrupt
    exceptions, because it is not possible to fake Vim internal exceptions.
    Trying so causes an error exception.  You should throw your own exception
    denoting the situation.  If you want to cause a Vim error exception containing
    the original error exception value, you can use the |:echoerr| command:

    	:try
    	:  try
    	:    asdf
    	:  catch /.*/
    	:    echoerr v:exception
    	:  endtry
    	:catch /.*/
    	:  echo v:exception
    	:endtry

    This code displays

    	Vim(echoerr):Vim:E492: Not an editor command:	asdf

    CLEANUP CODE						*try-finally*

    Scripts often change global settings and restore them at their end.  If the
    user however interrupts the script by pressing CTRL-C, the settings remain in
    an inconsistent state.  The same may happen to you in the development phase of
    a script when an error occurs or you explicitly throw an exception without
    catching it.  You can solve these problems by using a try conditional with
    a finally clause for restoring the settings.  Its execution is guaranteed on
    normal control flow, on error, on an explicit ":throw", and on interrupt.
    (Note that errors and interrupts from inside the try conditional are converted
    to exceptions.  When not caught, they terminate the script after the finally
    clause has been executed.)
    Example:

    	:try
    	:  let s:saved_ts = &ts
    	:  set ts=17
    	:
    	:  " Do the hard work here.
    	:
    	:finally
    	:  let &ts = s:saved_ts
    	:  unlet s:saved_ts
    	:endtry

    This method should be used locally whenever a function or part of a script
    changes global settings which need to be restored on failure or normal exit of
    that function or script part.

    							*break-finally*
    Cleanup code works also when the try block or a catch clause is left by
    a ":continue", ":break", ":return", or ":finish".
       Example:

    	:let first = 1
    	:while 1
    	:  try
    	:    if first
    	:      echo "first"
    	:      let first = 0
    	:      continue
    	:    else
    	:      throw "second"
    	:    endif
    	:  catch /.*/
    	:    echo v:exception
    	:    break
    	:  finally
    	:    echo "cleanup"
    	:  endtry
    	:  echo "still in while"
    	:endwhile
    	:echo "end"

    This displays "first", "cleanup", "second", "cleanup", and "end".

    	:function! Foo()
    	:  try
    	:    return 4711
    	:  finally
    	:    echo "cleanup\n"
    	:  endtry
    	:  echo "Foo still active"
    	:endfunction
    	:
    	:echo Foo() "returned by Foo"

    This displays "cleanup" and "4711 returned by Foo".  You don't need to add an
    extra ":return" in the finally clause.  (Above all, this would override the
    return value.)

    							*except-from-finally*
    Using either of ":continue", ":break", ":return", ":finish", or ":throw" in
    a finally clause is possible, but not recommended since it abandons the
    cleanup actions for the try conditional.  But, of course, interrupt and error
    exceptions might get raised from a finally clause.
       Example where an error in the finally clause stops an interrupt from
    working correctly:

    	:try
    	:  try
    	:    echo "Press CTRL-C for interrupt"
    	:    while 1
    	:    endwhile
    	:  finally
    	:    unlet novar
    	:  endtry
    	:catch /novar/
    	:endtry
    	:echo "Script still running"
    	:sleep 1

    If you need to put commands that could fail into a finally clause, you should
    think about catching or ignoring the errors in these commands, see
    |catch-errors| and |ignore-errors|.

    CATCHING ERRORS						*catch-errors*

    If you want to catch specific errors, you just have to put the code to be
    watched in a try block and add a catch clause for the error message.  The
    presence of the try conditional causes all errors to be converted to an
    exception.  No message is displayed and |v:errmsg| is not set then.  To find
    the right pattern for the ":catch" command, you have to know how the format of
    the error exception is.
       Error exceptions have the following format:

    	Vim({cmdname}):{errmsg}
    or
    	Vim:{errmsg}

    {cmdname} is the name of the command that failed; the second form is used when
    the command name is not known.  {errmsg} is the error message usually produced
    when the error occurs outside try conditionals.  It always begins with
    a capital "E", followed by a two or three-digit error number, a colon, and
    a space.

    Examples:

    The command
    	:unlet novar
    normally produces the error message
    	E108: No such variable: "novar"
    which is converted inside try conditionals to an exception
    	Vim(unlet):E108: No such variable: "novar"

    The command
    	:dwim
    normally produces the error message
    	E492: Not an editor command: dwim
    which is converted inside try conditionals to an exception
    	Vim:E492: Not an editor command: dwim

    You can catch all ":unlet" errors by a
    	:catch /^Vim(unlet):/
    or all errors for misspelled command names by a
    	:catch /^Vim:E492:/

    Some error messages may be produced by different commands:
    	:function nofunc
    and
    	:delfunction nofunc
    both produce the error message
    	E128: Function name must start with a capital: nofunc
    which is converted inside try conditionals to an exception
    	Vim(function):E128: Function name must start with a capital: nofunc
    or
    	Vim(delfunction):E128: Function name must start with a capital: nofunc
    respectively.  You can catch the error by its number independently on the
    command that caused it if you use the following pattern:
    	:catch /^Vim(\a\+):E128:/

    Some commands like
    	:let x = novar
    produce multiple error messages, here:
    	E121: Undefined variable: novar
    	E15: Invalid expression:  novar
    Only the first is used for the exception value, since it is the most specific
    one (see |except-several-errors|).  So you can catch it by
    	:catch /^Vim(\a\+):E121:/

    You can catch all errors related to the name "nofunc" by
    	:catch /\<nofunc\>/

    You can catch all Vim errors in the ":write" and ":read" commands by
    	:catch /^Vim(\(write\|read\)):E\d\+:/

    You can catch all Vim errors by the pattern
    	:catch /^Vim\((\a\+)\)\=:E\d\+:/

    							*catch-text*
    NOTE: You should never catch the error message text itself:
    	:catch /No such variable/
    only works in the English locale, but not when the user has selected
    a different language by the |:language| command.  It is however helpful to
    cite the message text in a comment:
    	:catch /^Vim(\a\+):E108:/   " No such variable

    IGNORING ERRORS						*ignore-errors*

    You can ignore errors in a specific Vim command by catching them locally:

    	:try
    	:  write
    	:catch
    	:endtry

    But you are strongly recommended NOT to use this simple form, since it could
    catch more than you want.  With the ":write" command, some autocommands could
    be executed and cause errors not related to writing, for instance:

    	:au BufWritePre * unlet novar

    There could even be such errors you are not responsible for as a script
    writer: a user of your script might have defined such autocommands.  You would
    then hide the error from the user.
       It is much better to use

    	:try
    	:  write
    	:catch /^Vim(write):/
    	:endtry

    which only catches real write errors.  So catch only what you'd like to ignore
    intentionally.

    For a single command that does not cause execution of autocommands, you could
    even suppress the conversion of errors to exceptions by the ":silent!"
    command:
    	:silent! nunmap k
    This works also when a try conditional is active.

    CATCHING INTERRUPTS					*catch-interrupt*

    When there are active try conditionals, an interrupt (CTRL-C) is converted to
    the exception "Vim:Interrupt".  You can catch it like every exception.  The
    script is not terminated, then.
       Example:

    	:function! TASK1()
    	:  sleep 10
    	:endfunction

    	:function! TASK2()
    	:  sleep 20
    	:endfunction

    	:while 1
    	:  let command = input("Type a command: ")
    	:  try
    	:    if command == ""
    	:      continue
    	:    elseif command == "END"
    	:      break
    	:    elseif command == "TASK1"
    	:      call TASK1()
    	:    elseif command == "TASK2"
    	:      call TASK2()
    	:    else
    	:      echo "\nIllegal command:" command
    	:      continue
    	:    endif
    	:  catch /^Vim:Interrupt$/
    	:    echo "\nCommand interrupted"
    	:    " Caught the interrupt.  Continue with next prompt.
    	:  endtry
    	:endwhile

    You can interrupt a task here by pressing CTRL-C; the script then asks for
    a new command.  If you press CTRL-C at the prompt, the script is terminated.

    For testing what happens when CTRL-C would be pressed on a specific line in
    your script, use the debug mode and execute the |>quit| or |>interrupt|
    command on that line.  See |debug-scripts|.

    CATCHING ALL						*catch-all*

    The commands

    	:catch /.*/
    	:catch //
    	:catch

    catch everything, error exceptions, interrupt exceptions and exceptions
    explicitly thrown by the |:throw| command.  This is useful at the top level of
    a script in order to catch unexpected things.
       Example:

    	:try
    	:
    	:  " do the hard work here
    	:
    	:catch /MyException/
    	:
    	:  " handle known problem
    	:
    	:catch /^Vim:Interrupt$/
    	:    echo "Script interrupted"
    	:catch /.*/
    	:  echo "Internal error (" .. v:exception .. ")"
    	:  echo " - occurred at " .. v:throwpoint
    	:endtry
    	:" end of script

    Note: Catching all might catch more things than you want.  Thus, you are
    strongly encouraged to catch only for problems that you can really handle by
    specifying a pattern argument to the ":catch".
       Example: Catching all could make it nearly impossible to interrupt a script
    by pressing CTRL-C:

    	:while 1
    	:  try
    	:    sleep 1
    	:  catch
    	:  endtry
    	:endwhile

    EXCEPTIONS AND AUTOCOMMANDS				*except-autocmd*

    Exceptions may be used during execution of autocommands.  Example:

    	:autocmd User x try
    	:autocmd User x   throw "Oops!"
    	:autocmd User x catch
    	:autocmd User x   echo v:exception
    	:autocmd User x endtry
    	:autocmd User x throw "Arrgh!"
    	:autocmd User x echo "Should not be displayed"
    	:
    	:try
    	:  doautocmd User x
    	:catch
    	:  echo v:exception
    	:endtry

    This displays "Oops!" and "Arrgh!".

    							*except-autocmd-Pre*
    For some commands, autocommands get executed before the main action of the
    command takes place.  If an exception is thrown and not caught in the sequence
    of autocommands, the sequence and the command that caused its execution are
    abandoned and the exception is propagated to the caller of the command.
       Example:

    	:autocmd BufWritePre * throw "FAIL"
    	:autocmd BufWritePre * echo "Should not be displayed"
    	:
    	:try
    	:  write
    	:catch
    	:  echo "Caught:" v:exception "from" v:throwpoint
    	:endtry

    Here, the ":write" command does not write the file currently being edited (as
    you can see by checking 'modified'), since the exception from the BufWritePre
    autocommand abandons the ":write".  The exception is then caught and the
    script displays:

    	Caught: FAIL from BufWrite Auto commands for "*"

    							*except-autocmd-Post*
    For some commands, autocommands get executed after the main action of the
    command has taken place.  If this main action fails and the command is inside
    an active try conditional, the autocommands are skipped and an error exception
    is thrown that can be caught by the caller of the command.
       Example:

    	:autocmd BufWritePost * echo "File successfully written!"
    	:
    	:try
    	:  write /i/m/p/o/s/s/i/b/l/e
    	:catch
    	:  echo v:exception
    	:endtry

    This just displays:

    	Vim(write):E212: Can't open file for writing (/i/m/p/o/s/s/i/b/l/e)

    If you really need to execute the autocommands even when the main action
    fails, trigger the event from the catch clause.
       Example:

    	:autocmd BufWritePre  * set noreadonly
    	:autocmd BufWritePost * set readonly
    	:
    	:try
    	:  write /i/m/p/o/s/s/i/b/l/e
    	:catch
    	:  doautocmd BufWritePost /i/m/p/o/s/s/i/b/l/e
    	:endtry

    You can also use ":silent!":

    	:let x = "ok"
    	:let v:errmsg = ""
    	:autocmd BufWritePost * if v:errmsg != ""
    	:autocmd BufWritePost *   let x = "after fail"
    	:autocmd BufWritePost * endif
    	:try
    	:  silent! write /i/m/p/o/s/s/i/b/l/e
    	:catch
    	:endtry
    	:echo x

    This displays "after fail".

    If the main action of the command does not fail, exceptions from the
    autocommands will be catchable by the caller of the command:

    	:autocmd BufWritePost * throw ":-("
    	:autocmd BufWritePost * echo "Should not be displayed"
    	:
    	:try
    	:  write
    	:catch
    	:  echo v:exception
    	:endtry

    							*except-autocmd-Cmd*
    For some commands, the normal action can be replaced by a sequence of
    autocommands.  Exceptions from that sequence will be catchable by the caller
    of the command.
       Example:  For the ":write" command, the caller cannot know whether the file
    had actually been written when the exception occurred.  You need to tell it in
    some way.

    	:if !exists("cnt")
    	:  let cnt = 0
    	:
    	:  autocmd BufWriteCmd * if &modified
    	:  autocmd BufWriteCmd *   let cnt = cnt + 1
    	:  autocmd BufWriteCmd *   if cnt % 3 == 2
    	:  autocmd BufWriteCmd *     throw "BufWriteCmdError"
    	:  autocmd BufWriteCmd *   endif
    	:  autocmd BufWriteCmd *   write | set nomodified
    	:  autocmd BufWriteCmd *   if cnt % 3 == 0
    	:  autocmd BufWriteCmd *     throw "BufWriteCmdError"
    	:  autocmd BufWriteCmd *   endif
    	:  autocmd BufWriteCmd *   echo "File successfully written!"
    	:  autocmd BufWriteCmd * endif
    	:endif
    	:
    	:try
    	:	write
    	:catch /^BufWriteCmdError$/
    	:  if &modified
    	:    echo "Error on writing (file contents not changed)"
    	:  else
    	:    echo "Error after writing"
    	:  endif
    	:catch /^Vim(write):/
    	:    echo "Error on writing"
    	:endtry

    When this script is sourced several times after making changes, it displays
    first
    	File successfully written!
    then
    	Error on writing (file contents not changed)
    then
    	Error after writing
    etc.

    							*except-autocmd-ill*
    You cannot spread a try conditional over autocommands for different events.
    The following code is ill-formed:

    	:autocmd BufWritePre  * try
    	:
    	:autocmd BufWritePost * catch
    	:autocmd BufWritePost *   echo v:exception
    	:autocmd BufWritePost * endtry
    	:
    	:write

    EXCEPTION HIERARCHIES AND PARAMETERIZED EXCEPTIONS	*except-hier-param*

    Some programming languages allow to use hierarchies of exception classes or to
    pass additional information with the object of an exception class.  You can do
    similar things in Vim.
       In order to throw an exception from a hierarchy, just throw the complete
    class name with the components separated by a colon, for instance throw the
    string "EXCEPT:MATHERR:OVERFLOW" for an overflow in a mathematical library.
       When you want to pass additional information with your exception class, add
    it in parentheses, for instance throw the string "EXCEPT:IO:WRITEERR(myfile)"
    for an error when writing "myfile".
       With the appropriate patterns in the ":catch" command, you can catch for
    base classes or derived classes of your hierarchy.  Additional information in
    parentheses can be cut out from |v:exception| with the ":substitute" command.
       Example:

    	:function! CheckRange(a, func)
    	:  if a:a < 0
    	:    throw "EXCEPT:MATHERR:RANGE(" .. a:func .. ")"
    	:  endif
    	:endfunction
    	:
    	:function! Add(a, b)
    	:  call CheckRange(a:a, "Add")
    	:  call CheckRange(a:b, "Add")
    	:  let c = a:a + a:b
    	:  if c < 0
    	:    throw "EXCEPT:MATHERR:OVERFLOW"
    	:  endif
    	:  return c
    	:endfunction
    	:
    	:function! Div(a, b)
    	:  call CheckRange(a:a, "Div")
    	:  call CheckRange(a:b, "Div")
    	:  if (a:b == 0)
    	:    throw "EXCEPT:MATHERR:ZERODIV"
    	:  endif
    	:  return a:a / a:b
    	:endfunction
    	:
    	:function! Write(file)
    	:  try
    	:    execute "write" fnameescape(a:file)
    	:  catch /^Vim(write):/
    	:    throw "EXCEPT:IO(" .. getcwd() .. ", " .. a:file .. "):WRITEERR"
    	:  endtry
    	:endfunction
    	:
    	:try
    	:
    	:  " something with arithmetic and I/O
    	:
    	:catch /^EXCEPT:MATHERR:RANGE/
    	:  let function = substitute(v:exception, '.*(\(\a\+\)).*', '\1', "")
    	:  echo "Range error in" function
    	:
    	:catch /^EXCEPT:MATHERR/	" catches OVERFLOW and ZERODIV
    	:  echo "Math error"
    	:
    	:catch /^EXCEPT:IO/
    	:  let dir = substitute(v:exception, '.*(\(.\+\),\s*.\+).*', '\1', "")
    	:  let file = substitute(v:exception, '.*(.\+,\s*\(.\+\)).*', '\1', "")
    	:  if file !~ '^/'
    	:    let file = dir .. "/" .. file
    	:  endif
    	:  echo 'I/O error for "' .. file .. '"'
    	:
    	:catch /^EXCEPT/
    	:  echo "Unspecified error"
    	:
    	:endtry

    The exceptions raised by Vim itself (on error or when pressing CTRL-C) use
    a flat hierarchy:  they are all in the "Vim" class.  You cannot throw yourself
    exceptions with the "Vim" prefix; they are reserved for Vim.
       Vim error exceptions are parameterized with the name of the command that
    failed, if known.  See |catch-errors|.

    PECULIARITIES
    							*except-compat*
    The exception handling concept requires that the command sequence causing the
    exception is aborted immediately and control is transferred to finally clauses
    and/or a catch clause.

    In the Vim script language there are cases where scripts and functions
    continue after an error: in functions without the "abort" flag or in a command
    after ":silent!", control flow goes to the following line, and outside
    functions, control flow goes to the line following the outermost ":endwhile"
    or ":endif".  On the other hand, errors should be catchable as exceptions
    (thus, requiring the immediate abortion).

    This problem has been solved by converting errors to exceptions and using
    immediate abortion (if not suppressed by ":silent!") only when a try
    conditional is active.  This is no restriction since an (error) exception can
    be caught only from an active try conditional.  If you want an immediate
    termination without catching the error, just use a try conditional without
    catch clause.  (You can cause cleanup code being executed before termination
    by specifying a finally clause.)

    When no try conditional is active, the usual abortion and continuation
    behavior is used instead of immediate abortion.  This ensures compatibility of
    scripts written for Vim 6.1 and earlier.

    However, when sourcing an existing script that does not use exception handling
    commands (or when calling one of its functions) from inside an active try
    conditional of a new script, you might change the control flow of the existing
    script on error.  You get the immediate abortion on error and can catch the
    error in the new script.  If however the sourced script suppresses error
    messages by using the ":silent!" command (checking for errors by testing
    |v:errmsg| if appropriate), its execution path is not changed.  The error is
    not converted to an exception.  (See |:silent|.)  So the only remaining cause
    where this happens is for scripts that don't care about errors and produce
    error messages.  You probably won't want to use such code from your new
    scripts.

    							*except-syntax-err*
    Syntax errors in the exception handling commands are never caught by any of
    the ":catch" commands of the try conditional they belong to.  Its finally
    clauses, however, is executed.
       Example:

    	:try
    	:  try
    	:    throw 4711
    	:  catch /\(/
    	:    echo "in catch with syntax error"
    	:  catch
    	:    echo "inner catch-all"
    	:  finally
    	:    echo "inner finally"
    	:  endtry
    	:catch
    	:  echo 'outer catch-all caught "' .. v:exception .. '"'
    	:  finally
    	:    echo "outer finally"
    	:endtry

    This displays:
        inner finally
        outer catch-all caught "Vim(catch):E54: Unmatched \("
        outer finally
    The original exception is discarded and an error exception is raised, instead.

    							*except-single-line*
    The ":try", ":catch", ":finally", and ":endtry" commands can be put on
    a single line, but then syntax errors may make it difficult to recognize the
    "catch" line, thus you better avoid this.
       Example:
    	:try | unlet! foo # | catch | endtry
    raises an error exception for the trailing characters after the ":unlet!"
    argument, but does not see the ":catch" and ":endtry" commands, so that the
    error exception is discarded and the "E488: Trailing characters" message gets
    displayed.

    							*except-several-errors*
    When several errors appear in a single command, the first error message is
    usually the most specific one and therefore converted to the error exception.
       Example:
    	echo novar
    causes
    	E121: Undefined variable: novar
    	E15: Invalid expression: novar
    The value of the error exception inside try conditionals is:
    	Vim(echo):E121: Undefined variable: novar
    							*except-syntax-error*
    But when a syntax error is detected after a normal error in the same command,
    the syntax error is used for the exception being thrown.
       Example:
    	unlet novar #
    causes
    	E108: No such variable: "novar"
    	E488: Trailing characters
    The value of the error exception inside try conditionals is:
    	Vim(unlet):E488: Trailing characters
    This is done because the syntax error might change the execution path in a way
    not intended by the user.  Example:
    	try
    	    try | unlet novar # | catch | echo v:exception | endtry
    	catch /.*/
    	    echo "outer catch:" v:exception
    	endtry
    This displays "outer catch: Vim(unlet):E488: Trailing characters", and then
    a "E600: Missing :endtry" error message is given, see |except-single-line|.

    9. Examples						*eval-examples*

    Printing in Binary

      :" The function Nr2Bin() returns the binary string representation of a number.
      :func Nr2Bin(nr)
      :  let n = a:nr
      :  let r = ""
      :  while n
      :    let r = '01'[n % 2] .. r
      :    let n = n / 2
      :  endwhile
      :  return r
      :endfunc

      :" The function String2Bin() converts each character in a string to a
      :" binary string, separated with dashes.
      :func String2Bin(str)
      :  let out = ''
      :  for ix in range(strlen(a:str))
      :    let out = out .. '-' .. Nr2Bin(char2nr(a:str[ix]))
      :  endfor
      :  return out[1:]
      :endfunc

    Example of its use:
      :echo Nr2Bin(32)
    result: "100000"
      :echo String2Bin("32")
    result: "110011-110010"

    Sorting lines

    This example sorts lines with a specific compare function.

      :func SortBuffer()
      :  let lines = getline(1, '$')
      :  call sort(lines, function("Strcmp"))
      :  call setline(1, lines)
      :endfunction

    As a one-liner:
      :call setline(1, sort(getline(1, '$'), function("Strcmp")))

    scanf() replacement
    							*sscanf*
    There is no sscanf() function in Vim.  If you need to extract parts from a
    line, you can use matchstr() and substitute() to do it.  This example shows
    how to get the file name, line number and column number out of a line like
    "foobar.txt, 123, 45".
       :" Set up the match bit
       :let mx='\(\f\+\),\s*\(\d\+\),\s*\(\d\+\)'
       :"get the part matching the whole expression
       :let l = matchstr(line, mx)
       :"get each item out of the match
       :let file = substitute(l, mx, '\1', '')
       :let lnum = substitute(l, mx, '\2', '')
       :let col = substitute(l, mx, '\3', '')

    The input is in the variable "line", the results in the variables "file",
    "lnum" and "col". (idea from Michael Geddes)

    getting the scriptnames in a Dictionary
    						*scriptnames-dictionary*
    The `:scriptnames` command can be used to get a list of all script files that
    have been sourced.  There is also the `getscriptinfo()` function, but the
    information returned is not exactly the same.  In case you need to manipulate
    the list, this code can be used as a base:

        # Create or update scripts dictionary, indexed by SNR, and return it.
        def Scripts(scripts: dict<string> = {}): dict<string>
          for info in getscriptinfo()
            if scripts->has_key(info.sid)
              continue
            endif
            scripts[info.sid] = info.name
          endfor
          return scripts
        enddef

    10. Vim script versions		*vimscript-version* *vimscript-versions*
    							*scriptversion*
    Over time many features have been added to Vim script.  This includes Ex
    commands, functions, variable types, etc.  Each individual feature can be
    checked with the |has()| and |exists()| functions.

    Sometimes old syntax of functionality gets in the way of making Vim better.
    When support is taken away this will break older Vim scripts.  To make this
    explicit the |:scriptversion| command can be used.  When a Vim script is not
    compatible with older versions of Vim this will give an explicit error,
    instead of failing in mysterious ways.

    When using a legacy function, defined with `:function`, in |Vim9| script then
    scriptversion 4 is used.

    							*scriptversion-1*
     :scriptversion 1
    	This is the original Vim script, same as not using a |:scriptversion|
    	command.  Can be used to go back to old syntax for a range of lines.
    	Test for support with:
    		has('vimscript-1')

    <							*scriptversion-2*
     :scriptversion 2
    	String concatenation with "." is not supported, use ".." instead.
    	This avoids the ambiguity using "." for Dict member access and
    	floating point numbers.  Now ".5" means the number 0.5.

    							*scriptversion-3*
     :scriptversion 3
    	All |vim-variable|s must be prefixed by "v:".  E.g. "version" doesn't
    	work as |v:version| anymore, it can be used as a normal variable.
    	Same for some obvious names as "count" and others.

    	Test for support with:
    		has('vimscript-3')

    							*scriptversion-4*
     :scriptversion 4
    	Numbers with a leading zero are not recognized as octal.  "0o" or "0O"
    	is still recognized as octal.  With the
    	previous version you get:
    		echo 017   " displays 15 (octal)
    		echo 0o17  " displays 15 (octal)
    		echo 018   " displays 18 (decimal)
    <	with script version 4:
    		echo 017   " displays 17 (decimal)
    		echo 0o17  " displays 15 (octal)
    		echo 018   " displays 18 (decimal)
    	Also, it is possible to use single quotes inside numbers to make them
    	easier to read:
    		echo 1'000'000
    	The quotes must be surrounded by digits.

    	Test for support with:
    		has('vimscript-4')

    11. No +eval feature				*no-eval-feature*

    When the |+eval| feature was disabled at compile time, none of the expression
    evaluation commands are available.  To prevent this from causing Vim scripts
    to generate all kinds of errors, the ":if" and ":endif" commands are still
    recognized, though the argument of the ":if" and everything between the ":if"
    and the matching ":endif" is ignored.  Nesting of ":if" blocks is allowed, but
    only if the commands are at the start of the line.  The ":else" command is not
    recognized.

    Example of how to avoid executing commands when the |+eval| feature is
    missing:

    	:if 1
    	:  echo "Expression evaluation is compiled in"
    	:else
    	:  echo "You will _never_ see this message"
    	:endif

    To execute a command only when the |+eval| feature is disabled can be done in
    two ways.  The simplest is to exit the script (or Vim) prematurely:
    	if 1
    	   echo "commands executed with +eval"
    	   finish
    	endif
    	args  " command executed without +eval

    If you do not want to abort loading the script you can use a trick, as this
    example shows:

    	silent! while 0
    	  set history=111
    	silent! endwhile

    When the |+eval| feature is available the command is skipped because of the
    "while 0".  Without the |+eval| feature the "while 0" is an error, which is
    silently ignored, and the command is executed.

    12. The sandbox					*eval-sandbox* *sandbox*

    The 'foldexpr', 'formatexpr', 'includeexpr', 'indentexpr', 'statusline' and
    'foldtext' options may be evaluated in a sandbox.  This means that you are
    protected from these expressions having nasty side effects.  This gives some
    safety for when these options are set from a modeline.  It is also used when
    the command from a tags file is executed and for CTRL-R = in the command line.
    The sandbox is also used for the |:sandbox| command.
    								*E48*
    These items are not allowed in the sandbox:
    	- changing the buffer text
    	- defining or changing mapping, autocommands, user commands
    	- setting certain options (see |option-summary|)
    	- setting certain v: variables (see |v:var|)  *E794*
    	- executing a shell command
    	- reading or writing a file
    	- jumping to another buffer or editing a file
    	- executing Python, Perl, etc. commands
    This is not guaranteed 100% secure, but it should block most attacks.

    							*:san* *:sandbox*
    :san[dbox] {cmd}	Execute {cmd} in the sandbox.  Useful to evaluate an
    			option that may have been set from a modeline, e.g.
    			'foldexpr'.

    							*sandbox-option*
    A few options contain an expression.  When this expression is evaluated it may
    have to be done in the sandbox to avoid a security risk.  But the sandbox is
    restrictive, thus this only happens when the option was set from an insecure
    location.  Insecure in this context are:
    - sourcing a .vimrc or .exrc in the current directory
    - while executing in the sandbox
    - value coming from a modeline
    - executing a function that was defined in the sandbox

    Note that when in the sandbox and saving an option value and restoring it, the
    option will still be marked as it was set in the sandbox.

    13. Textlock							*textlock*

    In a few situations it is not allowed to change the text in the buffer, jump
    to another window and some other things that might confuse or break what Vim
    is currently doing.  This mostly applies to things that happen when Vim is
    actually doing something else.  For example, evaluating the 'balloonexpr' may
    happen any moment the mouse cursor is resting at some position.

    This is not allowed when the textlock is active:
    	- changing the buffer text
    	- jumping to another buffer or window
    	- editing another file
    	- closing a window or quitting Vim
    	- etc.

    14. Vim script library					*vim-script-library*

    Vim comes bundled with a Vim script library, that can be used by runtime,
    script authors.  Currently, it only includes very few functions, but it may
    grow over time.

    The functions are available as |Vim9-script| as well as using legacy Vim
    script (to be used for non Vim 9.0 versions and Neovim).

    							*dist#vim* *dist#vim9*
    The functions make use of the autoloaded prefix "dist#vim" (for legacy Vim
    script and Neovim) and "dist#vim9" for Vim9 script.

    The following functions are available:

    dist#vim#IsSafeExecutable(filetype, executable)
    dist#vim9#IsSafeExecutable(filetype:string, executable:string): bool

    This function takes a filetype and an executable and checks whether it is safe
    to execute the given executable.  For security reasons users may not want to
    have Vim execute random executables or may have forbidden to do so for
    specific filetypes by setting the "<filetype>_exec" variable (|plugin_exec|).

    It returns |true| or |false| to indicate whether the plugin should run the
    given executable.  It takes the following arguments:

    	argument	type

    	filetype	string
    	executable	string

    							*package-open*
    The |:Open| and |:Launch| command are provided by the included plugin
    $VIMRUNTIME/plugin/openPlugin.vim

    					*dist#vim9#Open()* *:Open* *:URLOpen*
    						      *g:Openprg* *gx*
    dist#vim9#Open(file: string)

    Opens `path` with the system default handler (macOS `open`, Windows
    `explorer.exe`, Linux `xdg-open`, …). If the variable |g:Openprg| exists the
    string specified in the variable is used instead.

    The |:Open| user command uses file completion for its argument.

    The |:URLOpen| user command works the same but does not perform file
    completion and therefore does not expand special characters |cmdline-special|.

    This function is by default called using the gx mapping.  In visual mode
    tries to open the visually selected text.

    Associated setting variables:
    `g:gx_word`: control how gx picks up the text under the cursor. Uses
    	     `g:netrw_gx` as a fallback for backward compatibility.
    	     (default: `<cfile>`)

    `g:nogx`: disables the gx mapping. Uses `g:netrw_nogx` as a fallback for
    	  backward compatibility. (default: `unset`)

    NOTE: Escaping of the path is automatically applied.

    Usage: >vim
    	:call dist#vim9#Open(<path>)
    	:Open <path>
    	:URLOpen <path>
    <
    						*dist#vim9#Launch()* *:Launch*
    dist#vim9#Launch(file: string)

    Launches <args> with the appropriate system programs. Intended for launching
    GUI programs within Vim.

    The |:Launch| user command uses shell completion for its first argument.

    NOTE: escaping of <args> is left to the user

    Examples:
    	vim9script

    	import autoload 'dist/vim9.vim'
    	# Execute 'makeprg' into another xterm window
    	vim9.Launch('xterm ' .. expandcmd(&makeprg))

    Usage: >vim
    	:call dist#vim9#Launch(<args>)
    	:Launch <app> <args>.
    <

     vim:tw=78:ts=8:noet:ft=help:norl:

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