critcl - C Runtime In Tcl (CriTcl)

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# critcl(n) 3.1.17 doc "C Runtime In Tcl (CriTcl)"

## Name

critcl - Critcl - Package Reference

## Table Of Contents

## Synopsis

- package require Tcl 8.4
- package require critcl ?3.1.17?
- package require platform ?1.0.2?
- package require md5 ?2?

- ::critcl::ccode text
- ::critcl::ccommand tclname cfunname
- ::critcl::ccommand tclname arguments body ?option value...?
- ::critcl::cdata tclname data
- ::critcl::cconst tclname resulttype value
- ::critcl::cdefines definitions ?namespace?
- ::critcl::cproc name arguments resulttype body ?option value...?
- ::critcl::cproc name arguments resulttype
- ::critcl::cinit text externals
- ::critcl::include path
- ::critcl::api import name version
- ::critcl::api function resulttype name arguments
- ::critcl::api header ?pattern...?
- ::critcl::api extheader ?file...?
- ::critcl::license author ?text...?
- ::critcl::summary text
- ::critcl::description text
- ::critcl::subject ?key...?
- ::critcl::meta key ?word...?
- ::critcl::meta? key
- ::critcl::buildrequirement script
- ::critcl::cheaders ?arg...?
- ::critcl::csources ?pattern...?
- ::critcl::clibraries ?arg...?
- ::critcl::source path
- ::critcl::tsources pattern...
- ::critcl::owns pattern...
- ::critcl::cflags ?arg...?
- ::critcl::ldflags ?arg...?
- ::critcl::framework ?arg...?
- ::critcl::tcl version
- ::critcl::tk
- ::critcl::preload lib...
- ::critcl::debug area...
- ::critcl::check ?label? text
- ::critcl::checklink ?label? text
- ::critcl::msg ?-nonewline? msg
- ::critcl::print ?-nonewline? ?chan? msg
- ::critcl::compiled
- ::critcl::compiling
- ::critcl::done
- ::critcl::failed
- ::critcl::load
- ::critcl::config option ?val?
- ::critcl::cache ?path?
- ::critcl::clean_cache ?pattern...?
- ::critcl::readconfig path
- ::critcl::showconfig ?chan?
- ::critcl::showallconfig ?chan?
- ::critcl::chooseconfig target ?nomatcherr?
- ::critcl::setconfig target
- ::critcl::actualtarget
- ::critcl::buildforpackage ?flag?
- ::critcl::cnothingtodo file
- ::critcl::cresults ?file?
- ::critcl::crosscheck
- ::critcl::error msg
- ::critcl::knowntargets
- ::critcl::sharedlibext
- ::critcl::targetconfig
- ::critcl::buildplatform
- ::critcl::targetplatform
- ::critcl::cobjects ?arg...?
- ::critcl::scan path
- ::critcl::name2c name
- ::critcl::argnames arguments
- ::critcl::argcnames arguments
- ::critcl::argcsignature arguments
- ::critcl::argvardecls arguments
- ::critcl::argconversion arguments ?n?
- ::critcl::argoptional arguments
- ::critcl::argdefaults arguments
- ::critcl::argsupport arguments
- ::critcl::userconfig define name description type ?default?
- ::critcl::userconfig query name
- ::critcl::userconfig set name value
- ::critcl::at::caller
- ::critcl::at::caller offset
- ::critcl::at::caller offset level
- ::critcl::at::here
- ::critcl::at::get*
- ::critcl::at::get
- ::critcl::at::= file line
- ::critcl::at::incr n...
- ::critcl::at::incrt str...
- ::critcl::at::caller!
- ::critcl::at::caller! offset
- ::critcl::at::caller! offset level
- ::critcl::at::here!
- ::critcl::collect_begin
- ::critcl::collect_end
- ::critcl::collect script
- ::critcl::make path contents
- ::critcl::has-resulttype name
- ::critcl::resulttype name body ?ctype?
- ::critcl::resulttype name = origname
- ::critcl::has-argtype name
- ::critcl::argtype name body ?ctype? ?ctypefun?
- ::critcl::argtype name = origname
- ::critcl::argtypesupport name code ?guard?
- ::critcl::argtyperelease name code
- ::preload library

## Description

Welcome to the C Runtime In Tcl, CriTcl for short, a system to build C extension packages for Tcl on the fly, from C code embedded within Tcl scripts, for all who wish to make their code go faster.

This document is the reference manpage for the critcl package. This package is the system's core, i.e. it provides the essential functionality on top of which everything else is built. Its intended audience are mainly developers wishing to write Tcl packages with embedded C code. Some of its sections are however for developers wishing to understand the package internals, and the API it provides to the CriTcl Application. These sections will be marked, allowing package writers to skip them. Users of critcl on the other hand are hereby refered to the applications' manpage, i.e. CriTcl Application. If you are in need of an overview of the whole system instead, please go and read the Introduction To CriTcl.

This package resides in the Core Package Layer of CriTcl.

## API

A short note ahead of the documentation: Instead of repeatedly talking about "a ".tcl" with embbedded C code", or "a ".tcl" containing critcl commands", etc. we use a shorthand and simply call them ".critcl" files, regardless of their file extension.

### Embedded C Code

The package provides five commands to declare various types of C code fragments. These are:

::critcl::ccode text

  This command compiles the C code in text and makes the contained definitions (variables, functions, macros, etc.) available to all C code fragments specified after it. It itself can assume to have access to all definitions which were specified before it. See section Runtime Behaviour for more details.

  The result of the command is the empty string.

::critcl::ccommand tclname cfunname

  This command creates a new Tcl command named tclname which is implemented by the C function cfunname. It is expected that cfunname has the proper signature for a Tcl command function, and was declared already.

  The result of ::critcl::ccommand itself is the empty string.

::critcl::ccommand tclname arguments body ?option value...?

  This form of critcl::ccommand creates a new Tcl command named tclname which is implemented by the C code in body.

  The command wraps the body in an invisible C function, compiles it and makes the resulting definition available to all C code fragments declared later on. It itself can assume to have access to all definitions which came before it. See section Runtime Behaviour for more details.

  The result of critcl::ccommand itself is the empty string.

  The list of arguments contain the names for the four parameters required by a Tcl command function. Superfluous list elements (i.e. beyond the fourth) are ignored. Missing elements (parameters), and empty parameter names are handled by replacing them with standard names. These are, in order of usage

  1. clientdata

  2. interp

  3. objc

  4. objv

  The only options accepted by this command are:

  -clientdata c-expression

    The value of this option is the text of a single C expression. The value of expression is used in the generated C statement registering tclname to initialize the client data of the new Tcl command. If not specified the expression defaults to NULL, i.e. no client data.

  -delproc c-expression

    The value of this option is the text of a single C expression. The value of this expression has to be a function pointer of type "Tcl_CmdDeleteProc", which is used in the generated C statement registering tclname to initialize a deletion function for the new Tcl command, i.e. a function which is run by Tcl when the Tcl command is deleted again. If not specified the expression defaults to NULL, i.e. no deletion function.

  -cname boolean

    The value of this option is a boolean flag. If true the name of the command is the C identifier of the command function. Namespaces, etc. are in that case not relevant at all. The default value of this option is false, causing the system to derive a name from the Tcl level command name, including its namespace.

  A ccommand is, in comparison to functions defined via critcl::cproc, more lower level. Its advantage is that the developer can do their own argument processing, enabling things like variable number of arguments, options, etc., i.e. much higher flexibility. Their disadvantage is that you have to do your own argument processing. Where a critcl::cproc generates the code to convert from Tcl values to C values and back a critcl::ccommand forces the writer to do all of this on their own. I.e. the cost of the aforementioned flexibility is a higher complexity seen by the user.

::critcl::cdata tclname data

  This command creates a new Tcl command named tclname which returns data as a ByteArray result.

  The result of critcl::cdata itself is the empty string.

::critcl::cconst tclname resulttype value

  This command creates a new Tcl command named tclname which returns the constant value as its result, with Tcl type resulttype.

  The result of critcl::cconst itself is the empty string.

  The command is similar to critcl::cdata in that it returns a constant value. Contrary to critcl::cdata however it is not restricted to ByteArray results, but accepts all result-types known to critcl::cproc. Its semantics are actually equivalent to

          cproc $tclname {} $resulttype "return $value ;"

  Contrary to critcl::cproc however it is internally optimized to avoid generating a superfluous C function.

  Note that nothing prevents the user from using a C define for the value. Any visible C function is actually also allowed, as long as it does not take arguments.

::critcl::cdefines definitions ?namespace?

  This command creates Tcl variables in the specified namespace which are linked to the C enum values and #defines named as glob patterns in the list of definitions. Each variable has the same name as the definition which gave rise to it, and its value is the value of the corresponding enum value or #define. The namespace defaults to the global namespace, i.e. "::", if it wasn't specified explicitly.

  Please note that this command is only for the lifting of existing C definitions into Tcl. The command does not create the definitions in C. It actually goes so far to check for the presence of the named definitions and not performing the mapping for any which do not exist. Which is sensible, given that non-existing defines have no value which could be used in the mapping.

  As these checks are run at the time the embedded C code of a ".critcl" file is actually compiled they have access to and check all C fragments defined with critcl::ccode, plus all the headers it has access to via critcl::cheaders, for that file.

::critcl::cproc name arguments resulttype body ?option value...?

  This command creates a new Tcl command named tclname which is implemented by the C code in body. In contrast to the low-level critcl::ccommand here the arguments and result are typed and critcl generates the code converting from Tcl_Obj's to C data types, and vice versa. The command creates two invisible C functions, one wrapping the body, the other a shim containing the necessary conversions, compiles them and makes the resulting definitions available to all C code fragments declared later on. It itself can assume to have access to all definitions which came before it. See section Runtime Behaviour for more details.

  The result of critcl::cproc itself is the empty string.

  The only options accepted by this command are:

  -cname boolean

    The value of this option is a boolean flag. If true the name of the command is the C identifier of the command function. Namespaces, etc. are in that case not relevant at all. The default value of this option is false, causing the system to derive a name from the Tcl level command name, including its namespace.

  -pass-cdata boolean

    The value of this option is a boolean flag. If specified and set the shim translating from Tcl to C level and back will pass the command's ClientData to the function. If not specified the flag defaults to false, i.e. no passing of client data.

  -arg-offset int

    The value of this option is a positive integer number specifying the number of hidden arguments preceding the actual procedure arguments. If not specified the flag defaults to 0. This is useful to higher-order code generator using the command in settings with prefix arguments which are not directly seen by the function, but influence argument counting and extraction.

  Below is the list of predefined types legal for resulttype, plus the details of their semantics. Note that it is possible to extend this list with custom types if the standard does not support what is needed. See section Advanced: Extending cproc for details.

  Tcl_Obj*
  object

    The function returns a value of type Tcl_Obj*. This value becomes the interpreter result, if not 0. The Tcl status is TCL_ERROR when a 0 is returned, and TCL_OK otherwise.

    Note how it is the responsibility of the function to set the interpreter result to an appropriate error message when returning 0.

    Attention: The conversion assumes that the value belonged to the function, with an associated reference count, and decrements the reference count to indicate the loss of ownership by the function. This means that it is an error to return a value whose reference count is zero. The system will crash at some point after the return due to reuse of the freed memory.

  Tcl_Obj*0
  object0

    The function returns a value of type Tcl_Obj*. This value becomes the interpreter result, if not 0. The Tcl status is TCL_ERROR when a 0 is returned, and TCL_OK otherwise.

    Note how it is the responsibility of the function to set the interpreter result to an appropriate error message when returning 0.

    Attention: Contrary to Tcl_Obj* above this conversion assumes that the returned value has a reference count of 0 and performs no decrement. Returning a value whose reference count is greater than zero will likely cause a memory leak.

  char*
  vstring

    The function returns a value of type char*. This value becomes the interpreter result, wrapped in a String. It is assumed that the string is volatile in some way, with the wrapping in a String duplicating it before making it the result, ensuring that we will not access a dangling pointer in the future. The Tcl status is always TCL_OK.

  const char*

    Like type char* above, except that the returned string is const-qualified.

  string
  dstring

    The function returns a value of type char*. Contrary to the previous string types here it is assumed that the value is dynamically allocated, via Tcl_Alloc. This value becomes the interpreter result, as usual, but is not copied. The Tcl status is always TCL_OK.

  double

    The function returns a value of type double. This value becomes the interpreter result, properly wrapped as a Double. The Tcl status is always TCL_OK.

  float

    The function returns a value of type float. This value becomes the interpreter result, properly wrapped as a Double. The Tcl status is always TCL_OK.

  boolean
  bool

    The function returns a value of type int, interpreted as boolean. This value becomes the interpreter result, properly wrapped as a Int. The Tcl status is always TCL_OK.

  int

    The function returns a value of type int. This value becomes the interpreter result, properly wrapped as a Int. The Tcl status is always TCL_OK.

  long

    The function returns a value of type long int. This value becomes the interpreter result, properly wrapped as a Long. The Tcl status is always TCL_OK.

  wideint

    The function returns a value of type Tcl_WideInt. This value becomes the interpreter result, properly wrapped as a WideInt. The Tcl status is always TCL_OK.

  ok

    The function returns a value of type int. It is interpreted as the Tcl status code. The interpreter result is left untouched (empty). For a different outcome the function has to set the interpreter result by itself.

  void

    The function does not return a value. The interpreter result is left untouched (empty). For a different outcome the function has to set the interpreter result by itself. The Tcl status is always TCL_OK.

  The arguments parameter has the overall syntax of a Tcl dictionary value, except that keys (argument names) and values (argument types) are specified in reverse order. Consider the example

      int x int y

  where x and y are the arguments/keys, both mapped to type/value int.

  The argument names must be valid C identifiers.

  A limited form of variadic arguments is possible, through optional arguments with default values. For these the argument name is a 2-element list containing the actual name, and the default value. For example, in the declaration

       int {x 1}

  x is an optional argument of type int and default value 1.

  A caveat! The default value is assigned unconditionally. If a custom argument type uses more complex validation, and the default may be invalid according to it, then the relevant checks have to be done in the procedure body. The argument conversion cannot do it as it is completely bypassed when the argument is not present. Overcoming this requires the separation of argument conversion and validation code.

  Below is the list of predefined types legal for arguments, plus the details of their semantics. Note that it is possible to extend this list with custom types if the standard does not support what is needed. See section Advanced: Extending cproc for details.

  Further note that the type of the first argument is allowed to be Tcl_Interp*. In that case the argument in question is not counted as an argument of the new Tcl command.

  Tcl_Obj*
  object

    The function takes an argument of type Tcl_Obj*. No argument checking is done. The Tcl level word is passed to the argument as-is.

  pstring

    The function takes an argument of type critcl_pstring containing the original Tcl_Obj* reference of the Tcl argument, plus the length of the string and a pointer to the character array.

        typedef struct critcl_pstring {
            Tcl_Obj* o;
            char*    s;
            int      len;
        } critcl_pstring;

  list

    The function takes an argument of type critcl_list containing the original Tcl_Obj* reference of the Tcl argument, plus the length of the Tcl list and a pointer to the array of the list elements.

        typedef struct critcl_list {
            Tcl_Obj*  o;
            Tcl_Obj** v;
            int       c;
        } critcl_list;

    The Tcl argument must be convertible to List, an error is thrown otherwise.

  bytearray
  rawchar*
  rawchar

    The function takes an argument of type char*. The Tcl argument must be convertible to ByteArray, an error is thrown otherwise. Note that the length of the ByteArray is not passed to the function, making this type not very usable.

  bytes

    This is the new and usable ByteArray type.

    The function takes an argument of type critcl_bytes containing the original Tcl_Obj* reference of the Tcl argument, plus the length of the byte array and a pointer to the byte data.

        typedef struct critcl_bytes {
            Tcl_Obj* o;
            char*    s;
            int      len;
        } critcl_list;

    The Tcl argument must be convertible to ByteArray, an error is thrown otherwise.

  char*

    The function takes an argument of type char*. The string representation of the Tcl argument is passed in.

  double

    The function takes an argument of type double. The Tcl argument must be convertible to Double, an error is thrown otherwise.

  float

    The function takes an argument of type float. The Tcl argument must be convertible to Double, an error is thrown otherwise.

  boolean
  bool

    The function takes an argument of type int. The Tcl argument must be convertible to Boolean, an error is thrown otherwise.

  int

    The function takes an argument of type int. The Tcl argument must be convertible to Int, an error is thrown otherwise.

  long

    The function takes an argument of type long int. The Tcl argument must be convertible to Long, an error is thrown otherwise.

  wideint

    The function takes an argument of type Tcl_WideInt. The Tcl argument must be convertible to WideInt, an error is thrown otherwise.

  void*
  double*
  float*
  int*

    The function takes an argument of the same-named C type. The Tcl argument must be convertible to ByteArray, an error is thrown otherwise. The bytes in the ByteArray are then re-interpreted as the raw representation of a single C pointer of the given type which is then passed as argument to the function. In other words, this is for Tcl values somehow holding raw C pointers, i.e. memory addresses.

    Attention: These types are considered DEPRECATED. It is planned to remove their documentation in release 3.2, and their implementation in release 3.3. Their deprecation can be undone if good use cases are shown.

::critcl::cproc name arguments resulttype

  This variant of critcl::cproc assumes that the functionality to connect to is implemented by the C function name which has the signature described by the arguments and resulttype.

  It creates only the shim performing the conversions required by arguments and result.

::critcl::cinit text externals

  This command compiles the C code in text and externals.

  Both arguments have access to all definitions created by the previously listed commands, regardless of their placement in the ".critcl" file relative to this command. See section Runtime Behaviour for more details.

  The C code in text is put into the body of the initialization function of the shared library backing the ".critcl" file, and is executed when this library is loaded into the interpreter.

  This code has access to a variable interp of type Tcl_Interp* referencing the Tcl interpreter currently being initialized.

  The code in externals on the other hand is placed outside and just before the initialization function, making this is a good place for any external symbols required by initialization function which should not be accessible by any other parts of the C code.

  Multiple invokations of this command are allowed, and a later call has access to the information of all preceding ones.

  The result of the command is the empty string.

::critcl::include path

  This command is a convenient shorthand for

      critcl::code {
        #include <${path}>
      }

### Stubs Table Management

Newly introduced with critcl version 3 is the support for stubs tables, Tcl's dynamic linking mechanism handling the resolution of symbols between C extensions. We won't go into its details here. See http://wiki.tcl.tk/285 for an introduction in general, and section Stubs Tables for the details of critcl's particular variant.

Critcl supports this via a single command, critcl::api, and its methods.

First, importing stubs tables, i.e. APIs, from another extension:

::critcl::api import name version

  Critcl prepares the ".critcl" file and its companion ".c" files by including the headers

  1. "name/nameDecls.h"

  2. "name/nameStubLib.h"

  in the appropriate places. It is checked that the compiler will be able to find these header files somewhere on the include search path, using the paths defined so far (See critcl::cheaders, and the critcl application's -I and -includedir options). Note how critcl expects the headers of package foo to reside in a sub-directory "foo" of the known include search paths.

  Important: If foo is a namespaced package name, like, for example "c::stack", then the namespace separators "::" are converted into underscores ("_") in path names, C code, etc.

  The first header is expected to contain contains all the necessary stubs table type declarations, mapping macros, etc., and may include package specific headers (See critcl::api header below). This header is included at the beginning of the C code backing the ".critcl" file, and at the beginning of all companion ".c" files. This means that the writer of these files doesn't have to write the necessary #include directory, critcl does it for them.

  The second header is expected to contain the stubs table variable definition, and the C code, i.e. definition, of the function to initialize it. This, and a call to this initializer function are added to the ".critcl" file's initialization code.

  If the directory containing the aforementioned headers also contains the file "name/name.decls" then it is assumed that this file contains the external representation of the stubs table used to generate the headers. The file is read and the internal representation of the stubs table returned as result of the command, for the importing package to use as it sees fit. If no such file is present the command returns the empty string as its result.

  One possible use would be the automatic generation of C code calling on the functions listed in the imported API.

  When generating a TEA wrapper the names of the imported APIs are used to declare configure options with which the user can declare a non-standard location for the headers of the API. Any API FOO is translated a single configure option --with-FOO-include.

Second, declaration and export of a stubs table, i.e. API, for the current package, foo:

::critcl::api function resulttype name arguments

  This method declares that the function name is in the public API of the package, and its signature (type of the result, number, names and types of its arguments). Using this method automatically causes critcl to generate both the code for a stubs table in the package, the headers needed by packages using this API, and a ".decls" file containing the stubs table implied by the exports, usable by critcl::api import.

  arguments is a list of C types and associated argument names. Like a dictionary, except that keys (argument names) and values (argument types) are swapped. The resulttype is a C type as well.

::critcl::api header ?pattern...?

  This method notifies critcl of companion header files which have to be exported together with the generated stubs headers.

  All arguments are interpreted as glob pattern and the matching files are copied into the directory containing the generated headers well. As an importing package uses only "fooDecls.h" to access the API this generated header will contain the necessary #include directives to make these companion header files and their declarations available too. Patterns matching no file or non-existing files cause the command to throw an error.

  Note that patterns which are not beginning with an absolute path are interpreted relative to the directory containing the current ".critcl" file.

::critcl::api extheader ?file...?

  This method is similar ::critcl::api header, in that it notifies critcl of companion header files which have to be exported together with the generated stubs headers.

  The difference is that these headers will be expected to exist in the external development environment. As such they will be #included in the generated header for the package, but not copied to the package header directory. Nor are they allowed to be glob patterns, as critcl has no context, i.e directory, in which to expand such patterns.

Note that the generated headers for an exported API are included in the package like it is done when importing it somewhere else. To repeat:

The "fooDecls.h" header is included at the beginning of the C code backing the ".critcl" file, and at the beginning of all companion ".c" files. This means that the writer of these files doesn't have to write the necessary #include directory, critcl does it for them.

In mode "compile & run" the generated header files, and their companion headers, if any, are placed in the subdirectory "foo" of the Result Cache. As this location is implicitly added to the include search path any other package importing this API and and build in mode "compile & run" as well will find the these headers.

For mode "generate package" the application was extended with a new option -includedir which specifies the location to place the generated headers in (again in subdirectory "foo" of that path). This path is also be added to the include search paths, ensuring that a package importing an API will find it if the package exporting that API used the same setting for -includedir.

For mode "generate TEA" the static scanner was extended to recognize critcl::api header as a source of companion files. It further uses data about critcl::api import commands to put proper support for --with-foo-include options into the generate "configure(.in)" so that a user may specify custom locations for the headers of any imported API.

### Package Meta Data

Newly introduced with critcl version 3 is support for TEApot meta-data.

While, from the package developer's perspective, some meta data support was already present in critcl v2, through the command ::critcl::license, this was only used to generate and place a file "license.txt" into the built package.

Now critcl supports the declaration of arbitrary meta data, which will be placed into a file "teapot.txt" in a format suitable for use by the TEApot tools.

::critcl::license author ?text...?

  This command provides information about the author of the package, and its license.

  If no text is present the command expects to find a file "license.terms" in the same directory as the ".critcl" file and reads the license from that. Otherwise the license is the joined texts.

  This information, the license, is ignored in mode "compile & run", only mode "generate package" uses it. In that case the information is written to a file "license.terms", a sibling to the "pkgIndex.tcl" file in the directory hierarchy of the generated package.

  This information is additionally placed into the meta data file "teapot.txt", under the keys as::author and license.

  The data specified by this command has priority over any information specified through the generic API ::critcl::meta.

::critcl::summary text

  Declares a short (one line is recommended) description of the package.

  This information is ignored in mode "compile & run", only mode "generate package" uses it. In that case the information is placed into the meta data file "teapot.txt", under the key summary.

  The data specified by this command has priority over any information specified through the generic API ::critcl::meta.

::critcl::description text

  Declares a longer description of the package.

  This information is ignored in mode "compile & run", only mode "generate package" uses it. In that case the information is placed into the meta data file "teapot.txt", under the key description.

  The data specified by this command has priority over any information specified through the generic API ::critcl::meta.

::critcl::subject ?key...?

  Declares one or more keywords and key-phrases describing the package, for an index.

  Multiple calls of this command accumulate keywords and phrases.

  This information is ignored in mode "compile & run", only mode "generate package" uses it. In that case the information is placed into the meta data file "teapot.txt", under the key subject.

  The data specified by this command has priority over any information specified through the generic API ::critcl::meta.

::critcl::meta key ?word...?

  This command is for the declaration of arbitrary meta data outside of the reserved keys as::author, as::build::date, description, license, name, platform, require subject, summary, and version, Its behaviour is like ::critcl::subject, in that it treats all keys as list of words, with each call declaring one or more words for the key, and multiple calls extending the data for an existing key, if not reserved.

  While it is possible to declare information for one of the reserved keys with this command such data is ignored when the final meta data is assembled and written.

  Use the commands ::critcl::license, ::critcl::summary, ::critcl::description ::critcl::subject, package require, and package provide to declare data for the reserved keys.

  The information for the reserved keys as::build::date and platform is automatically generated by critcl itself.

::critcl::meta? key

  This command enables the retrieval of meta data information from with the code defining a critcl based package. Given the key the associated value is returned as the result of the command.

  The envisioned main use is the retrieval of the package's name from within utility packages having to adapt C code templates to their environment. An example of a package using this command for exactly this purpose is critcl::class.

::critcl::buildrequirement script

  This command provides control over the capturing of dependencies declared via package require. It runs the script, and any dependencies declared within are ignored, i.e. not recorded in the meta data.

### Control & Interface

The package provides thirteen commands to control the details of compilation and linking, enabling ".critcl" files to provide custom information about their environment and dependencies.

In important thing to note about all these commands is that the package manages their information on a per-file basis. I.e. information provided by and in a file "FOO.tcl" is kept separate from the information provided by and in a file "BAR.tcl", preventing them from interfering with each other.

The commands are:

::critcl::cheaders ?arg...?

  This command provides the compile step with additional header files and header locations.

  All arguments matching the glob pattern -* are forwarded to the compiler's command line when it is invoked for the current ".critcl" file.

  All other arguments are interpreted as glob pattern and the matching files are made available to the compiler when it is invoked for the current ".critcl" file. Patterns matching no file or non-existing files cause the command to throw an error.

  Note that patterns which are not beginning with an absolute path are interpreted relative to the directory containing the current ".critcl" file.

  Note further that this declaration does not cause the specified header files to be automatically #include'd. Inclusion still has to be done via either critcl::include or critcl::ccode, where necessary. It does simply ensure that the compiler will be able to find these files when invoked, by providing the necessary command line flags to extend the compiler's search paths.

  Multiple invocations of this command accumulate their information.

::critcl::csources ?pattern...?

  This command provides the compile step with additional C source files.

  All arguments are interpreted as glob patterns. Patterns matching no file or non-existing files cause the command to throw an error. The files matching the patterns are made available to the compiler when it is invoked for the current ".critcl" file. This means that the files in question are compiled together with the ".c" file backing the ".critcl" file into a single object.

  Note that patterns which are not beginning with an absolute path are interpreted relative to the directory containing the current ".critcl" file.

  Multiple invocations of this command accumulate their information.

::critcl::clibraries ?arg...?

  This command provides the link step with additional libraries to link and library locations.

  All arguments matching the glob pattern -* are forwarded to the linkers's command line when it is invoked for the current ".critcl" file.

  All other arguments are interpreted glob patterns. Patterns matching no file or non-existing files cause the command to throw an error. The files matching the patterns are made available to the linker when it is invoked for the current ".critcl" file. This means that the files in question are linked together with the object file backing the ".critcl" file into a single shared library.

  Note that patterns which are not beginning with an absolute path are interpreted relative to the directory containing the current ".critcl" file.

  Multiple invocations of this command accumulate their information.

::critcl::source path

  This command evaluates the critcl commands in the file specified by path in the context of the current ".critcl" file.

  The argument is actually considered as glob pattern and all matching files are evaluated. A pattern matching no file or non-existing files cause the command to throw an error.

  Note that a pattern not beginning with an absolute path is interpreted relative to the directory containing the current ".critcl" file.

::critcl::tsources pattern...

  This command provides the critcl package with information about additional Tcl script files to source when the shared library is loaded.

  All arguments are considered as glob patterns and the matching files are made available to generated shared library when it is loaded for the current ".critcl" file. Patterns matching no file or non-existing files cause the command to throw an error.

  Note that patterns which are not beginning with an absolute path are interpreted relative to the directory containing the current ".critcl" file.

  Multiple invocations of this command accumulate their information.

  The declared files are sourced after the shared library has been loaded, in the same order they were provided to critcl::tsources.

::critcl::owns pattern...

  This command is ignored by the regular build modes, i.e. both "compile and run", and "generate package". It is present to support the static code scanner of critcl v3's new mode to "generate TEA" packages.

  In that situation it provides the critcl package with information about any files which have to be wrapped and could not be figured out from the previous commands (i.e. critcl::csources, critcl::tsources) because of getting specified dynamically, or getting directly sourced and this not visible to critcl in any other way.

::critcl::cflags ?arg...?

  This command provides the compile step with additional compiler flags.

  All arguments are forwarded to the compiler's command line when it is invoked for the current ".critcl" file.

  Multiple invocations of this command accumulate their information.

::critcl::ldflags ?arg...?

  This command provides the link step with additional linker flags.

  All arguments are forwarded to the linkers's command line when it is invoked for the current ".critcl" file.

  Multiple invocations of this command accumulate their information.

::critcl::framework ?arg...?

  This command provides the link step with the names of additional frameworks to link on MacOS X. The command is ignored if we are not building for OS X. This means that it is possible to declare the OS X specific frameworks unconditionally. The package itself takes care to not use them when building for non-OS X platforms.

  All arguments are forwarded to the linkers's command line when it is invoked for the current ".critcl" file.

  Multiple invocations of this command accumulate their information.

::critcl::tcl version

  This command tells critcl for what minimum version of the Tcl runtime to compile and link the package for. If not specified critcl falls back to the default of 8.4.

::critcl::tk

  This command informs critcl that the package in question is based on Tk, and therefore needs the Tk headers for compilation, and the Tk stubs for linking.

::critcl::preload lib...

  This command arranges that the named dependent external shared library is loaded before the generated package's shared library.

  Multiple invocations of this command accumulate their information.

  Each library FOO named for preload will be searched at the locations listed below, in the order listed, and the search will stop on the first existing path. Additional notes:

  - platform is the placeholder for the target platform of the package.

  - The extension ".so" is the placeholder for whatever actual extension is used by the target platform for its shared libraries.

  - Note how the search is relative to the current working directory.

  And now the paths, depending on the exact form of the library name:

  FOO

    1. FOO.so

    2. FOO/FOO.so

    3. FOO/platform/FOO.so

  PATH/FOO

    For this form the exact set searched depends on the existence of directory "PATH/FOO". If it does not exist critcl searches

    1. FOO.so

    2. PATH/FOO.so

    3. PATH/platform/FOO.so

    Otherwise it searches

    1. FOO.so

    2. PATH/FOO/FOO.so

    3. PATH/FOO/platform/FOO.so

    instead.

  /PATH/FOO

    Even when specifying FOO with an absolute path the first path searched is relative to the current working directory.

    1. FOO.so

    2. /PATH/FOO.so

    3. /PATH/platform/FOO.so

  If you are a developer wishing to understand or modify the internals of the critcl package then you possibly should read the section explaining how the Preloading functionality is implemented.

::critcl::debug area...

  This tells critcl if the package is to be compiled for debugging, and which areas to activate. Internally each area is translated into area-specific flags for the compiler which are then handed over to critcl::cflags.

  memory

    Specification of this area activates Tcl memory debugging for the package code.

  symbols

    Specification of this area activates compilation and linking with debugging symbols, for use by a debugger or other tool.

  all

    Specification of this area translates ino the activation of all other legal areas.

### Introspection

The package provides six commands to control compilation and linking. These are:

::critcl::check ?label? text

  This command is useful to test if some functionality is available in the build environment, and then select other C code fragments based on that information. It immediately compiles the C code in text and returns a boolean value based on the result of the compilation. The command returns true on success, and false otherwise. If specified, the label is used to uniquely mark the check in the generated log.

::critcl::checklink ?label? text

  This command is an extenson of critcl::check above, useful to test if some functionality is available in the build environment, and then select other C code fragments based on that information. It immediately compiles and links the C code in text and returns a boolean value based on the result of compilation and linking. The command returns true on success, and false otherwise. If specified, the label is used to uniquely mark the check in the generated log.

::critcl::msg ?-nonewline? msg

  This command can be used by critc-based code to report results from critcl::check and critcl::checklink. The default implementation used by mode compile & run ignores any calls.

  Tools like the CriTcl Application are allowed to redefine this procedure to perform their own way of message reporting. The package critcl::app and the application on top print such messages to stdout, for example.

::critcl::print ?-nonewline? ?chan? msg

  This command is used by the critcl internals to report its activity. Its signature is equivalent to the Tcl builtin command ::puts. The default implementation is effectively ::puts.

  Tools directly using either the critcl package, or the critcl application package are allowed to redefine this procedure to perform their own way of printing.

  An example of this is Kettle where the newest revisions use this to highlight build warnings.

::critcl::compiled

  This command returns a boolean value. It returns true if the C code of the current ".critcl" file is already compiled, and false otherwise.

  This predicate effectively enables a ".critcl" file used as its own Tcl companion file (see critcl::tsources) to distinguish between sourced by mode "compile & run" for compilation and sourced from either the result of mode "generate package" or during the load phase of "compile & run". In case of the two latter possibilities the result is true, and false for the first.

::critcl::compiling

  This command returns a boolean value. It returns true if C code can be compiled on this platform in general, i.e. if a C compiler is available, and false otherwise.

::critcl::done

  This command returns a boolean value. It returns true when critcl has built the embedded C code, and false otherwise.

  This enables the Tcl code of a critcl-based package to distinguish between it getting used as a prebuilt package, versus dynamic compile & run, and take action based on that.

  Note that this command is only useful from within a ".critcl" file. The result is managed on a per-file basis, like is done for the commands embedding C code and controlling the behaviour of compiler and linker.

  See also section Modes Of Operation/Use.

::critcl::failed

  This command returns a boolean value. It returns true if critcl has failed to build the package, and false otherwise, i.e. success. As part of this it forces the building of the package, but not its loading. Note that it will attempt to build the package only on the first call; future calls for the same package will return a cached result.

  This enables a critcl-based package to check itself for availability and throw an error if it could not be built. Note that the command does not throw such an error itself.

  Note further that this command is only useful from within in a ".critcl" file. The result is managed on a per-file basis, like is done for the commands embedding C code and controlling the behaviour of compiler and linker.

::critcl::load

  This command is like critcl::failed, except that it also forces the loading of the generated shared library, if it was built, and that its result has reversed sense.

  It returns true if critcl succeeded in building and loading the package, and false otherwise, i.e. build- or load-failure.

  This enables a critcl-based package to to not only check itself for availability and throw an error if it could not be built, but also force an immediate load, circumventing the default behaviour, which is lazy. See also section Runtime Behaviour. Note that the command does not throw any error itself.

  Note further that this command is only useful from within in a ".critcl" file. The result is managed on a per-file basis, like is done for the commands embedding C code and controlling the behaviour of compiler and linker.

### Build Management

The package provides a single command for the management of global settings, i.e. configuration options which are independent of any ".critcl" file.

It is expected that this command is irrelevant to anybody just wishing to write a ".critcl" file. It is a management command which is only useful to the CriTcl Application or similar tools.

::critcl::config option ?val?

  This command sets and returns critcl's global configuration options. These are

  force bool

    This flag tells the package whether it should force the building of C files despite having a cached shared library (when true, or not. The default is off.

  lines bool

    This flag tells the package whether to embed #line directives into the generated C code (when true) or not. By default this is on.

  trace bool

    Inactive by default. When active code tracing entry and exit of critcl::cproc-based is inserted into the C code. This implicitly activates the tracing facility in general. (See package critcl::cutil).

    Side note: This facility requires the use of a tclsh supporting the builtin info frame command. If critcl is run by a tclsh not supporting this no #line directives will be emitted. The command is supported by Tcl 8.5 and higher. It is also supported by Tcl 8.4 provided that it was compiled with the define -DTCL_TIP280. An example of such is ActiveState's ActiveTcl.

    Developers of higher-level packages generating their own C code, either directly, or indirectly, by using critcl commands, should also read section Advanced: Location management to see how critcl helps them in generating their directives. Examples of such packages come with critcl itself, see the packages critcl::iassoc and critcl::class.

  I path

    A single global include path to use for all files. Not set by default.

  combine enum
    dynamic

      Object files have the suffix _pic.

    static

      Object files have the suffix _stub.

    standalone

      Object files have no suffix, and the generated C files are compiled without using Tcl/Tk stubs. The result are object files usable for static linking into a big shell.

    The default is dynamic.

  language string
  keepsrc bool

    This flag tells the package whether to keep the generated ".c" files after it has build their ".o" files (when true), or not. The default is off.

  outdir path

    The path where to place a generated shared library. Not set by default, causing placement into the Result Cache.

### Result Cache Management

This package provides two commands for the management of the Result Cache. See that section for background information.

NOTE that these commands are irrelevant to anybody just wishing to write a package using critcl for the C parts. They are management commands which are only useful to the CriTcl Application or similar tools.

::critcl::cache ?path?

  This command sets and returns the path to the directory for the package's result cache.

  The default location is "~/.critcl/[platform::generic]" and usually does not require any changes.

::critcl::clean_cache ?pattern...?

  This command cleans the result cache, i.e. removes any and all files and directories in it. If one or more patterns are specified then only the files and directories matching them are removed.

### Build Configuration

This package provides four commands for the management of the build configuration, i.e. the per-platform information about compilers, linkers, and their commandline options.

NOTE that these commands are irrelevant to anybody just wishing to write a package using critcl for the C parts. They are management commands which are only useful to the CriTcl Application or similar tools.

::critcl::readconfig path

  This command reads the build configuration file at path and configures the package using the information for the currently set target platform.

::critcl::showconfig ?chan?

  This command converts the currently active build configuration into a human-readable string and prints the result to the channel chan. If chan is not present the string is instead returned as the result of the command.

::critcl::showallconfig ?chan?

  This command converts the set of all known build configurations (from the currently active build configuration file last set with critcl::readconfig) into a string and print the result to the channel chan. If chan is not present the string is instead returned as the result of the command.

::critcl::chooseconfig target ?nomatcherr?

  This command takes a target identifier and matches it against all known targets, returning a list containing all the matching ones. This search is first done on an exact basis, and then via glob matching. If no known target matches the argument the default is to return an empty list. However, if the boolean nomatcherr is specified and set, and error will be thrown instead, using critcl::error.

::critcl::setconfig target

  This command takes a target identifier and configures the package to use all its settings.

### Tool API

The twelve commands in this section provide tools like CriTcl Application or similar with deeper access to the package's internals. These commands are irrelevant to anybody just wishing to write a ".critcl" file.

::critcl::actualtarget

  This command returns the platform identifier of the target platform, i.e. the platform the generated code will be built for. In contrast to ::critcl::targetplatform this is the true target, with any cross-compilation information resolved.

::critcl::buildforpackage ?flag?

  This command signals whether the next file to be build is built for inclusion into a package or not. If not specified the flag defaults to true, i.e. building for a package. This disables a number of things in the backend, namely the linking of that file into a shared library, and loading such. It is expected that the build results are later wrapped into a larger collection.

::critcl::cnothingtodo file

  This command checks whether there is anything to build for file.

::critcl::cresults ?file?

  This command returns the build result information for the specified file. If no file is specified the information is taken from info script. The result in question is a Tcl dictionary with the following keys, and their meanings:

  clibraries

    The list of external shared libraries, and/or locations thereof to link the file needs for successful linking.

  ldflags

    The list of linker flags needed by the file for successful linking.

  license

    The license the package in the file is under. A string.

  mintcl

    The minimum version of Tcl required by the package in the file to run successfully. A proper Tcl version number.

  objects

    The list of object files backing the file, to be linked.

  preload

    The list of libraries the generated package has to preload to allow the package in the file to run successfully.

  tk

    A boolean indicating whether the package in the file has to be linked against Tk or not.

  tsources

    The list of companion ".tcl" files to source for the package in the ".critcl" file to run successfully.

  log

    The full build log generated by the compiler/linker, including command line data from critcl, and other things.

  exl

    The raw build log generated by the compiler/linker. This key contains only the output generated by the invoked applications.

::critcl::crosscheck

  This command checks if the package is configured for cross-compilation and prints a message to the standard error channel if so.

::critcl::error msg

  This command is used by the package to report internal errors. The default implementation simply throws the error. Tools like the CriTcl Application are allowed to redefine this procedure to perform their own way of error reporting. There is one constraint they are not allowed to change: The procedure must not return to the caller.

::critcl::knowntargets

  This command returns a list containing the identifiers of all targets found during the last invocation of critcl::readconfig.

::critcl::sharedlibext

  This command returns the file extension used by shared libraries on the target platform.

::critcl::targetconfig

  This command returns the target identifier chosen to by either system or user to build code for.

::critcl::buildplatform

  This command returns the platform identifier of the build platform, i.e. where the package is running on.

::critcl::targetplatform

  This command returns the platform identifier of the target platform, i.e. the platform the generated code will be built for. In contrast to ::critcl::actualtarget this may be the name of a cross-compilation target.

::critcl::cobjects ?arg...?

  This command is like ::critcl::clibraries, provides the link step with additional information. Instead of libraries the arguments are object files however. Despite this similarity it is not listed in section Control & Interface because it is of no use to package writers. Only tools like the CriTcl Application have need of it.

  All arguments are interpreted glob patterns. Patterns matching no file or non-existing files cause the command to throw an error. The files matching the patterns are made available to the linker when it is invoked for the current ".critcl" file. This means that the files in question are linked together with the object file backing the ".critcl" file into a single shared library.

  Note that patterns which are not beginning with an absolute path are interpreted relative to the directory containing the current ".critcl" file.

  Multiple invocations of this command accumulate their information.

::critcl::scan path

  This command is the main entry point to critcl's static code scanner. Invoked for a single ".critcl" file it returns a dictionary providing the following pieces information about it:

  version

    Package version.

  org

    Author(ing organization).

  files

    List of the companion files. The paths in this list are all relative to the location (directory) of the input file.

  This command and the information it returns can be used by tools to implement processing modes like the assembly of a directory hierarchy containing a TEA-lookalike buildystem, etc.

::critcl::name2c name

  This command exposes the conversion of a Tcl level identifier of commands into various C-level pieces, i.e. Tcl namespace prefix, C namespace prefix, Tcl base name, and C base name.

  The result of the command is a list of 4 elements providing the above mentioned information, in the named order.

  The envisioned main use is from within utility packages providing Tcl commands without going through the standard commands, i.e. critcl::ccommand, or critcl::cproc. An example of a package using this command for exactly this purpose is critcl::class.

### Advanced: Embedded C Code

For the advanced user five commands used inside of critcl::cproc are exposed. These are:

::critcl::argnames arguments

  This command takes an argument declaration as taken by critcl::cproc and returns a list of the user visible arguments found in the declaration.

::critcl::argcnames arguments

  This command takes an argument declaration as taken by critcl::cproc and returns a list of the C side variable names for the user visible arguments found in the declaration. The names returned here match the names used in the declarations and code returned by ::critcl::argvardecls and ::critcl::argconversion.

::critcl::argcsignature arguments

  This command takes an argument declaration as taken by critcl::cproc and returns a list of C parameter declarations for all arguments found in the declaration.

::critcl::argvardecls arguments

  This command takes an argument declaration as taken by critcl::cproc and returns a list of C side variable declarations for the user visible arguments found in the declaration. The names used in these declarations match the names returned by ::critcl::argcnames.

::critcl::argconversion arguments ?n?

  This command takes an argument declaration as taken by critcl::cproc and returns a list of C code fragments converting the user visible arguments found in the declaration from Tcl_Obj* to C types. The names used in these statements match the names returned by ::critcl::argcnames.

  The generated code assumes that the procedure arguments start at index n of the objv array. If this argument is not specified 1 will be assumed.

::critcl::argoptional arguments

  This command takes an argument declaration as taken by critcl::cproc and returns a list of boolean values indicating which arguments are optional (true) and not (false).

::critcl::argdefaults arguments

  This command takes an argument declaration as taken by critcl::cproc and returns a list containing the default values for all optional arguments.

::critcl::argsupport arguments

  This command takes an argument declaration as taken by critcl::cproc and returns a list of C code fragments needed to define the necessary supporting types.

### Custom Build Configuration

This package provides one command for the management of package-specific, i.e. developer-specified custom build configuration options.

::critcl::userconfig define name description type ?default?

  This command defines custom build configuration option, with description, type and optional default value.

  The type can be either bool, or a list of values.

  1. For bool the default value, if specified, must be a boolean. If it is not specified it defaults to true.

  2. For a list of values the default value, if specified, must be a value found in this list. If it is not specified it defaults to the first value of the list.

  The description serves as in-code documentation of the meaning of the option and is otherwise ignored. When generating a TEA wrapper the description is used for the configure option derived from the option declared by the command.

  A boolean option FOO are translated into a pair of configure options, --enable-FOO and --disable-FOO, whereas an option whose type is a list of values is translated into a single configure option --with-FOO.

::critcl::userconfig query name

  This command queries the database of custom build configuration option for the current ".critcl" file and returns the chosen value. This may be the default if no value was set via ::critcl::userconfig set.

  It is at this point that definitions and set values are brought together, with the latter validated against the definition.

::critcl::userconfig set name value

  This command is for use by a tool, like the critcl application, to specify values for custom build configuration options.

  At the time this command is used only the association between option name and value is recorded, and nothing else is done. This behaviour is necessary as the system may not know if an option of the specified name exists when the command is invoked, nor its type.

  Any and all validation is defered to when the value of an option is asked for via ::critcl::userconfig query.

  This means that it is possible to set values for any option we like, and the value will take effect only if such an option is both defined and used later on.

### Advanced: Location management

First a small introduction for whose asking themselves 'what is location management' ?

By default critcl embeds #line directives into the generated C code so that any errors, warnings and notes found by the C compiler during compilation will refer to the ".critcl" file the faulty code comes from, instead of the generated ".c" file.

Side note: This facility requires the use of a tclsh supporting the builtin info frame command. If critcl is run by a tclsh not supporting this no #line directives will be emitted. The command is supported by Tcl 8.5 and higher. It is also supported by Tcl 8.4 provided that it was compiled with the define -DTCL_TIP280. An example of such is ActiveState's ActiveTcl.

Most users will not care about this feature beyond simply wanting it to work and getting proper code references when reading compiler output.

Developers of higher-level packages generating their own C code however should care about this, to ensure that their generated code contains proper references as well. Especially as this is key to separating bugs concerning code generated by the package itself and bug in the user's code going into the package, if any.

Examples of such packages come with critcl itself, see the implementation of packages critcl::iassoc and critcl::class.

To help such developers eight commands are provided to manage such location information. These are listed below.

A main concept is that they all operate on a single stored location, setting, returning and clearing it. Note that this location information is completely independent of the generation of #line directives within critcl itself.

::critcl::at::caller

  This command stores the location of the caller of the current procedure as a tuple of file name and linenumber. Any previously stored location is overwritten. The result of the command is the empty string.

::critcl::at::caller offset

  As above, the stored line number is modified by the specified offset. In essence an implicit call of critcl::at::incr.

::critcl::at::caller offset level

  As above, but the level the location information is taken from is modified as well. Level 0 is the caller, -1 its caller, etc.

::critcl::at::here

  This command stores the current location in the current procedure as a tuple of file name and linenumber. Any previously stored location is overwritten. The result of the command is the empty string.

  In terms of ::critcl::at::caller this is equivalent to

      	critcl::at::caller 0 1

::critcl::at::get*

  This command takes the stored location and returns a formatted #line directive ready for embedding into some C code. The stored location is left untouched. Note that the directive contains its own closing newline.

  For proper nesting and use it is recommended that such directives are always added to the beginning of a code fragment. This way, should deeper layers add their own directives these will come before ours and thus be inactive. End result is that the outermost layer generating a directive will 'win', i.e. have its directive used. As it should be.

::critcl::at::get

  This command is like the above, except that it also clears the stored location.

::critcl::at::= file line

  This command allows the caller to set the stored location to anything they want, outside of critcl's control. The result of the command is the empty string.

::critcl::at::incr n...
::critcl::at::incrt str...

  These commands allow the user to modify the line number of the stored location, changing it incrementally. The increment is specified as either a series of integer numbers (incr), or a series of strings to consider (incrt). In case of the latter the delta is the number of lines endings found in the strings.

::critcl::at::caller!
::critcl::at::caller! offset
::critcl::at::caller! offset level
::critcl::at::here!

  These are convenience commands combining caller and here with get. I.e. they store the location and immediately return it formatted as proper #line directive. Also note that after their use the stored location is cleared.

### Advanced: Diversions

Diversions are for higher-level packages generating their own C code, to make their use of critcl's commands generating Embedded C Code easier.

These commands normally generate all of their C code for the current ".critcl" file, which may not be what is wanted by a higher-level package.

With a diversion the generator output can be redirected into memory and from there on then handled and processed as the caller desires before it is committed to an actual ".c" file.

An example of such a package comes with critcl itself, see the implementation of package critcl::class.

To help such developers three commands are provided to manage diversions and the collection of C code in memory. These are:

::critcl::collect_begin

  This command starts the diversion of C code collection into memory.

  The result of the command is the empty string.

  Multiple calls are allowed, with each call opening a new nesting level of diversion.

::critcl::collect_end

  This command end the diversion of C code collection into memory and returns the collected C code.

  If multiple levels of diversion are open the call only closes and returns the data from the last level.

  The command will throw an error if no diversion is active, indicating a mismatch in the pairing of collect_begin and collect_end.

::critcl::collect script

  This is a convenience command which runs the script under diversion and returns the collected C code, ensuring the correct pairing of collect_begin and collect_end.

### Advanced: File Generation

While file generation is related to the diversions explained in the previous section they are not the same. Even so, like diversions this feature is for higher-level packages generating their own C code.

Three examples of utility packages using this facility comes with critcl itself. See the implementations of packages critcl::literals, critcl::bitmap, and critcl::enum.

When splitting a package implementation into pieces it is often sensible to have a number of pure C companion files containing low-level code, yet these files may require information about the code in the main ".critcl" file. Such declarations are normally not exportable and using the stub table support does not make sense, as this is completely internal to the package.

With the file generation command below the main ".critcl" file can generate any number of header files for the C companions to pick up.

::critcl::make path contents

  This command creates the file path in a location where the C companion files of the package are able to pick it up by simple inclusion of path during their compilation, without interfering with the outer system at all.

  The generated file will contain the specified contents.

### Advanced: Extending cproc

While the critcl::cproc command understands the most common C types (see section Embedded C Code), sometimes this is not enough.

To get around this limitation the commands in this section enable users of critcl to extend the set of argument and result types understood by critcl::cproc. In other words, they allow them to define their own, custom, types.

::critcl::has-resulttype name

  This command tests if the named result-type is known or not. It returns a boolean value, true if the type is known and false otherwise.

::critcl::resulttype name body ?ctype?

  This command defines the result type name, and associates it with the C code doing the conversion (body) from C to Tcl. The C return type of the associated function, also the C type of the result variable, is ctype. This type defaults to name if it is not specified.

  If name is declared already an error will be thrown. Attention! The standard result type void is special as it has no accompanying result variable. This cannot be expressed by this extension command.

  The body's responsibility is the conversion of the functions result into a Tcl result and a Tcl status. The first has to be set into the interpreter we are in, and the second has to be returned.

  The C code of body is guaranteed to be called last in the wrapper around the actual implementation of the cproc in question and has access to the following environment:

  interp

    A Tcl_Interp* typed C variable referencing the interpreter the result has to be stored into.

  rv

    The C variable holding the result to convert, of type ctype.

  As examples here are the definitions of two standard result types:

          resulttype int {
      	Tcl_SetObjResult(interp, Tcl_NewIntObj(rv));
      	return TCL_OK;
          }
          resulttype ok {
      	/* interp result must be set by cproc body */
      	return rv;
          } int

::critcl::resulttype name = origname

  This form of the resulttype command declares name as an alias of result type origname, which has to be defined already. If this is not the case an error is thrown.

::critcl::has-argtype name

  This command tests if the named argument-type is known or not. It returns a boolean value, true if the type is known and false otherwise.

::critcl::argtype name body ?ctype? ?ctypefun?

  This command defines the argument type name, and associates it with the C code doing the conversion (body) from Tcl to C The C type of the variable to hold the conversion result is ctype and the type of the function argument itself is ctypefun. Both types default to name if they are not specified (or the empty string).

  If name is declared already an error will be thrown.

  The body's responsibility is the conversion of a command's Tcl_Obj* argument into a C value for the underlying function and its storage in a helper variable.

  The C code of body is guaranteed to be called inside of a separate C code block (thus allowing the use of local variables) which has access to the following environment:

  interp

    A Tcl_Interp* typed C variable referencing the interpreter the code is running in.

  @@

    A placeholder for the Tcl_Obj*-valued C expression providing the value of the argument to convert.

  @A

    A placeholder for the name of the C variable to store the converted argument into.

  As examples here are the definitions of two standard argument types:

          argtype int {
      	if (Tcl_GetIntFromObj(interp, @@, &@A) != TCL_OK) return TCL_ERROR;
          }
          argtype float {
      	double t;
      	if (Tcl_GetDoubleFromObj(interp, @@, &t) != TCL_OK) return TCL_ERROR;
      	@A = (float) t;
          }

::critcl::argtype name = origname

  This form of the argtype command declares name as an alias of argument type origname, which has to be defined already. If this is not the case an error is thrown.

::critcl::argtypesupport name code ?guard?

  This command defines a C code fragment for the already defined argument type name which will be inserted before all functions using that type. Its purpose is the definition of any supporting C types needed by the argument type. If the type is used by many functions the system ensures that only the first of the multiple insertions of the code fragment is active, and the others disabled. The guard identifier is normally derived from name, but can also be set explicitly, via guard. This latter allows different custom types to share a common support structure without having to perform their own guarding.

::critcl::argtyperelease name code

  This command defines a C code fragment for the already defined argument type name which will be inserted whenever the worker function of a critcl::cproc returns to the shim. It is the responsibility of this fragment to unconditionally release any resources the critcl::argtype conversion code allocated. An example of this are the variadic types for the support of the special, variadic args argument to critcl::cproc's. They allocate a C array for the collected arguments which has to be released when the worker returns. This command defines the C code for doing that.

## Concepts

### Modes Of Operation/Use

CriTcl can be used in three different modes of operation, called

1. Compile & Run, and

2. Generate Package

3. Generate TEA Package

Of these three Compile & Run came first and is the default when using the package directly. In that case the package collects the C fragments, builds them as needed, and caches the results for quick reuse when the same code is used in the future again.

The second mode, Generate Package, was introduced to enable the creation of (prebuilt) deliverable packages which do not depend on the existence of a build system, i.e. C compiler, on the target machine. This was originally done through the experimental Critbind tool, and is now handled by the CriTcl Application, also named critcl.

Newly introduced with Critcl version 3 is Generate TEA Package. This mode constructs a directory hierarchy from the package which can later be built like a regular TEA package, i.e. using

    	.../configure --prefix ...
    	make all isntall

Regarding the caching of results please read the section about the Result Cache fore more details.

### Runtime Behaviour

The default behaviour of critcl, the package is to defer the compilation, linking, and loading of any C code as much as possible, given that this is an expensive operation, mainly in the time required. In other words, the C code embedded into a ".critcl" file is built only when the first C command or procedure it provides is invoked. This part of the system uses standard functionality built into the Tcl core, i.e. the auto_index variable to map from commands to scripts providing them and the unknown command using this information when the command is needed.

A limitation of this behaviour is that it is not possible to just use info commands check for the existence of a critcl defined command. It is also necessary to search in the auto_index array, in case it has not been build yet.

This behaviour can be changed by using the control command critcl::load. When invoked, the building, including loading of the result, is forced. After this command has been invoked for a ".critcl" file further definition of C code in this file is not allowed any longer.

### File Mapping

Each ".critcl" file is backed by a single private ".c" file containing that code, plus the boilerplate necessary for its compilation and linking as a single shared library.

The Embedded C Code fragments appear in that file in the exact same order they were defined in the ".critcl" file, with one exception. The C code provided via critcl::cinit is put after all other fragments. In other words all fragments have access to the symbols defined by earlier fragments, and the critcl::cinit fragment has access to all, regardless of its placement in the ".critcl" file.

Note: A limitation of the current system is the near impossibility of C level access between different critcl-based packages. The issue is not the necessity of writing and sharing the proper extern statements, but that the management (export and import) of package-specific stubs-tables is not supported. This means that dependent parts have to be forcibly loaded before their user, with all that entails. See section Runtime Behaviour for the relevant critcl limitation, and remember that many older platforms do not support the necessary resolution of symbols, the reason why stubs were invented for Tcl in the first place.

### Result Cache

The compilation of C code is time-consuming critcl not only defers it as much as possible, as described in section Runtime Behaviour, but also caches the results.

This means that on the first use of a ".critcl" file "FOO.tcl" the resulting object file and shared library are saved into the cache, and on future uses of the same file reused, i.e. loaded directly without requiring compilation, provided that the contents of "FOO.tcl" did not change.

The change detection is based MD5 hashes. A single hash is computed for each ".critcl" file, based on hashes for all C code fragments and configuration options, i.e. everything which affects the resulting binary.

As long as the input file doesn't change as per the hash a previously built shared library found in the cache is reused, bypassing the compilation and link stages.

The command to manage the cache are found in section Result Cache Management. Note however that they are useful only to tools based on the package, like the CriTcl Application. Package writers have no need of them.

As a last note, the default directory for the cache is chosen based on the chosen build target. This means that the cache can be put on a shared (network) filesystem without having to fear interference between machines of different architectures.

### Preloading functionality

The audience of this section are developers wishing to understand and possibly modify the internals of critcl package and application. Package writers can skip this section.

It explains how the preloading of external libraries is realized.

Whenever a package declares libraries for preloading critcl will build a supporting shared library providing a Tcl package named "preload". This package is not distributed separately, but as part of the package requiring the preload functionality. This support package exports a single Tcl command

::preload library

  which is invoked once per libraries to preload, with the absolute path of that library. The command then loads the library.

  On windows the command will further use the Tcl command ::critcl::runtime::precopy to copy the library to the disk, should its path be in a virtual filesystem which doesn't directly support the loading of a shared library from it.

The command ::critcl::runtime::precopy is provided by the file "critcl-rt.tcl" in the generated package, as is the command ::critcl::runtime::loadlib which generates the ifneeded script expected by Tcl's package management. This generated ifneeded script contains the invocations of ::preload.

The C code for the supporting library is found in the file "critcl_c/preload.c", which is part of the critcl package.

The Tcl code for the supporting runtime "critcl-rt.tcl" is found in the file "runtime.tcl", which is part of the critcl::app package.

### Configuration Internals

The audience of this section are developers wishing to understand and possibly modify the internals of critcl package and application. Package writers can skip this section.

It explains the syntax of configuration files and the configuration keys used by critcl to configure its build backend, i.e. how this part of the system accesses compiler, linker, etc.

It is recommended to open the file containing the standard configurations ("path/to/critcl/Config") in the editor of your choice when reading this section of the documentation, using it as an extended set of examples going beyond the simple defaults shown here.

First, the keys and the meaning of their values, plus examples drawn from the standard configurations distributed with the package. Note that when writing a custom configuration it is not necessary to specify all the keys listed below, but only those whose default values are wrong or insufficient for the platform in question.

version

  The command to print the compiler version number. Defaults to

       gcc -v

compile

  The command to compile a single C source file to an object file. Defaults to

       gcc -c -fPIC

debug_memory

  The list of flags for the compiler to enable memory debugging in Tcl. Defaults to

       -DTCL_MEM_DEBUG

debug_symbols

  The list of flags for the compiler to add symbols to the object files and the resulting library. Defaults to

       -g

include

  The compiler flag to add an include directory. Defaults to

       -I

tclstubs

  The compiler flag to set USE_TCL_STUBS. Defaults to

       -DUSE_TCL_STUBS

tkstubs

  The compiler flag to set USE_TK_STUBS. Defaults to

       -DUSE_TK_STUBS

threadflags

  The list of compiler flags to enable a threaded build. Defaults to

          -DUSE_THREAD_ALLOC=1 -D_REENTRANT=1 -D_THREAD_SAFE=1
          -DHAVE_PTHREAD_ATTR_SETSTACKSIZE=1 -DHAVE_READDIR_R=1
          -DTCL_THREADS=1

  .

noassert

  The compiler flag to turn off assertions in Tcl code. Defaults to

       -DNDEBUG

optimize

  The compiler flag to specify optimization level. Defaults to

       -O2

output

  The compiler flags to set the output file of a compilation. Defaults to

       -o [list $outfile]

  NOTE the use of Tcl commands and variables here. At the time critcl uses the value of this key the value of the referenced variable is substituted into it. The named variable is the only variable whose value is defined for this substitution.

object

  The file extension for object files on the platform. Defaults to

       .o

preproc_define

  The command to preprocess a C source file without compiling it, but leaving #define's in the output. Defaults to

       gcc -E -dM

preproc_enum

  See preproc_define, except that #define's are not left in the output. Defaults to

       gcc -E

link

  The command to link one or more object files and create a shared library. Defaults to

       gcc -shared

link_preload

  The list of linker flags to use when dependent libraries are pre-loaded. Defaults to

       --unresolved-symbols=ignore-in-shared-libs

strip

  The flag to tell the linker to strip symbols from the shared library. Defaults to

       -Wl,-s

ldoutput

  Like output, but for the linker. Defaults to the value of output.

link_debug

  The list of linker flags needed to build a shared library with symbols. Defaults to the empty string. One platform requiring this are all variants of Windows, which uses

       -debug:full -debugtype:cv

link_release

  The list of linker flags needed to build a shared library without symbols, i.e. a regular build. Defaults to the empty string. One platform requiring this are all variants of Windows, which uses

       -release -opt:ref -opt:icf,3 -ws:aggressive

sharedlibext

  The file extension for shared library files on the platform. Defaults to

       [info sharedlibextension]

platform

  The identifier of the platform used in generated packages. Defaults to

       [platform::generic]

target

  The presence of this key marks the configuration as a cross-compilation target and the value is the actual platform identifier of the target. No default.

The syntax expected from configuration files is governed by the rules below. Again, it is recommended to open the file containing the standard configurations ("path/to/critcl/Config") in the editor of your choice when reading this section of the documentation, using it as an extended set of examples for the syntax>

1. Each logical line of the configuration file consists of one or more physical lines. In case of the latter the physical lines have to follow each other and all but the first must be marked by a trailing backslash. This is the same marker for continuation lines as used by Tcl itself.

2. A (logical) line starting with the character "#" (modulo whitespace) is a comment which runs until the end of the line, and is otherwise ignored.

3. A (logical) line starting with the word "if" (modulo whitespace) is interpreted as Tcl's if command and executed as such. I.e. this command has to follow Tcl's syntax for the command, which may stretch across multiple logical lines. The command will be run in a save interpreter.

4. A (logical) line starting with the word "set" (modulo whitespace) is interpreted as Tcl's set command and executed as such. I.e. this command has to follow Tcl's syntax for the command, which may stretch across multiple logical lines. The command will be run in a save interpreter.

5. A line of the form "platform variable value" defines a platform specific configuration variable and value. The variable has to be the name of one of the configuration keys listed earlier in this section, and the platform string identifies the platform the setting is for. All settings with the same identification string form the configuration block for this platform.

6. A line of the special form "platform when expression" marks the platform and all the settings in its configuration block as conditional on the expression.

   If the build platform is not a prefix of platform, nor vice versa the whole block is ignored. Otherwise the expression is evaluated via expr, in the same safe interpreter used to run any set and if commands found in the configuration file (see above).

   If the expression evaluates to true this configuration block is considered to be the build platform fo the host and chosen as the default configuration. An large example of of this feature is the handling of OS X found in the standard configuration file, where it selects the architectures to build based on the version of the operating system, the available SDK, etc. I.e. it chooses whether the output is universal or not, and whether it is old-style (ix86 + ppc) versus new-style (ix86 32+64) of universality.

7. A line of the special form "platform copy sourceplatform" copies the configuration variables and values currently defined in the configuration block for sourceplatform to that of platform, overwriting existing values, and creating missing ones. Variables of platform not defined by by sourceplatform are not touched.

   The copied values can be overridden later in the configuration file. Multiple copy lines may exist for a platform and be intermixed with normal configuration definitions. If a variable is defined multiple times, the last definition will be used.

8. At last, a line of the form "variable value" defines a default configuration variable and value.

### Stubs Tables

This section is for developers of extensions not based on critcl, yet also wishing to interface with stubs as they are understood and used by critcl, either by exporting their own stubs table to a critcl-based extension, or importing a stubs table of a critcl-based extension into their own.

To this end we describe the stubs table information of a package foo.

1. Note that the differences in the capitalization of "foo", "Foo", "FOO", etc. below demonstrate how to capitalize the actual package name in each context.

2. All relevant files must be available in a sub-directory "foo" which can be found on the include search paths.

3. The above directory may contain a file "foo.decls". If present it is assumed to contain the external representation of the stubs table the headers mentioned in the following items are based on.

   critcl is able to use such a file to give the importing package programmatic access to the imported API, for automatic code generation and the like.

4. The above directory must contain a header file "fooDecls.h". This file declares the exported API. It is used by both exporting and importing packages. It is usually generated and must contain (in the order specified):

   1. the declarations of the exported, i.e. public, functions of foo,

   2. the declaration of structure "FooStubs" for the stub table,

   3. the C preprocessor macros which route the invocations of the public functions through the stubs table.

      These macros must be defined if, and only if, the C preprocessor macro USE_FOO_STUBS is defined. Package foo does not define this macro, as it is allowed to use the exported functions directly. All importing packages however must define this macro, to ensure that they do not use any of the exported functions directly, but only through the stubs table.

   4. If the exported functions need additional types for their proper declaration then these types should be put into a separate header file (of arbitrary name) and "fooDecls.h" should contain an #include directive to this header at the top.

   A very reduced, yet also complete example, from a package for low-level random number generator functions can be found at the end of this section.

5. The above directory must contain a header file "fooStubLib.h". This file defines everything needed to use the API of foo. Consequently it is used only by importing packages. It is usually generated and must contain (in the order specified):

   1. An #include directive for "tcl.h", with USE_TCL_STUBS surely defined.

   2. An #include directive for "fooDecls.h", with USE_FOO_STUBS surely defined.

   3. A definition of the stubs table variable, i.e.

          const FooStubs* fooStubsPtr;

   4. A definition of the stubs initializer function, like

          char *
          Foo_InitStubs(Tcl_Interp *interp, CONST char *version, int exact)
          {
              /*
               * Boiler plate C code initalizing the stubs table variable,
               * i.e. "fooStubsPtr".
               */
              CONST char *actualVersion;
              actualVersion = Tcl_PkgRequireEx(interp, "foo", version,
          				     exact, (ClientData *) &fooStubsPtr);
              if (!actualVersion) {
          	return NULL;
              }
              if (!fooStubsPtr) {
          	Tcl_SetResult(interp,
          		      "This implementation of Foo does not support stubs",
          		      TCL_STATIC);
          	return NULL;
              }
              return (char*) actualVersion;
          }

   This header file must be included by an importing package exactly once, so that it contains only one definition of both stubs table and stubs initializer function.

   The importing package's initialization function must further contain a statement like

       if (!Foo_InitStubs (ip, "1", 0)) {
           return TCL_ERROR;
       }

   which invokes foo's stubs initializer function to set the local stub table up.

   For a complete example of such a header file see below, at the end of this section.

6. The last item above, about "fooStubLib.h" differs from the regular stub stable system used by Tcl. The regular system assumes that a static library "libfoostub.a" was installed by package foo, and links it.

   IMVHO critcl's approach is simpler, using only header files found in a single location, vs. header files and static library found in multiple, different locations.

   A second simplification is that we avoid having to extend critcl's compiler backend with settings for the creation of static libraries.

Below is a complete set of example header files, reduced, yet still complete, from a package for low-level random number generator functions:

"rngDecls.h":

      #ifndef rng_DECLS_H
      #define rng_DECLS_H
      #include <tcl.h>
      /*
       * Exported function declarations:
       */
      /* 0 */
      EXTERN void rng_bernoulli(double p, int*v);
      typedef struct RngStubs {
          int magic;
          const struct RngStubHooks *hooks;
          void (*rng_bernoulli) (double p, int*v); /* 0 */
      } RngStubs;
      #ifdef __cplusplus
      extern "C" {
      #endif
      extern const RngStubs *rngStubsPtr;
      #ifdef __cplusplus
      }
      #endif
      #if defined(USE_RNG_STUBS)
      /*
       * Inline function declarations:
       */
      #define rng_bernoulli  (rngStubsPtr->rng_bernoulli) /* 0 */
      #endif /* defined(USE_RNG_STUBS) */
      #endif /* rng_DECLS_H */

"rngStubLib.h":

      /*
       * rngStubLib.c --
       *
       * Stub object that will be statically linked into extensions that wish
       * to access rng.
       */
      #ifndef USE_TCL_STUBS
      #define USE_TCL_STUBS
      #endif
      #undef  USE_TCL_STUB_PROCS
      #include <tcl.h>
      #ifndef USE_RNG_STUBS
      #define USE_RNG_STUBS
      #endif
      #undef  USE_RNG_STUB_PROCS
      #include "rngDecls.h"
      /*
       * Ensure that Rng_InitStubs is built as an exported symbol.  The other stub
       * functions should be built as non-exported symbols.
       */
      #undef  TCL_STORAGE_CLASS
      #define TCL_STORAGE_CLASS DLLEXPORT
      const RngStubs* rngStubsPtr;

      /*
       *----------------------------------------------------------------------
       *
       * Rng_InitStubs --
       *
       * Checks that the correct version of Rng is loaded and that it
       * supports stubs. It then initialises the stub table pointers.
       *
       * Results:
       *  The actual version of Rng that satisfies the request, or
       *  NULL to indicate that an error occurred.
       *
       * Side effects:
       *  Sets the stub table pointers.
       *
       *----------------------------------------------------------------------
       */
      #ifdef Rng_InitStubs
      #undef Rng_InitStubs
      #endif
      char *
      Rng_InitStubs(Tcl_Interp *interp, CONST char *version, int exact)
      {
          CONST char *actualVersion;
          actualVersion = Tcl_PkgRequireEx(interp, "rng", version,
      				     exact, (ClientData *) &rngStubsPtr);
          if (!actualVersion) {
      	return NULL;
          }
          if (!rngStubsPtr) {
      	Tcl_SetResult(interp,
      		      "This implementation of Rng does not support stubs",
      		      TCL_STATIC);
      	return NULL;
          }
          return (char*) actualVersion;
      }

## Examples

As the set of examples is a bit large, and growing, it has been put into a separate document. Please see section "Embedding C" in the document about Using CriTcl.

The latest changes are found at the top.

## Changes for version 3.1.17

1. Extension: Allow duplicate arg- and result-type definitions if they are fully identical.

2. Bugfix. The application mishandled the possibility of identical-named critcl::tsources. Possible because critcl::tsources can be in subdirectories, a structure which is not retained in the assembled package, causing such files to overwrite each other and at least one lost. Fixed by adding a serial number to the file names in the assembled package.

3. Bugfix in the static scanner which made it loose requirement information. Further added code to generally cleanup results at the end (removal of duplicates, mainly).

4. Bugfix: Fixed issue #76. Support installation directories which are not in the auto_path. Without the patch the installed critcl will not find its own packages and fail. Thank you to Simon Bachmann for the report and patch, and then his patience with me to getting to actually apply it.

5. Bugfix: Fixed issue #75. Extended critcl::include to now take multiple paths.

6. Added new compatibility package lmap84.

7. Fixed typos in various documentation files.

8. Fixed bug introduced by commit 86f415dd30 (3.1.16 release). The separation of critcl::ccode into user and work layers means that location retrieval has to go one more level up to find the user location.

9. New supporting package critcl::cutil. Provides common C level facilities useful to packages (assertions, tracing, memory allocation shorthands).

10. Modified package critcl to make use of the new tracing facilities to provide tracing of arguments and results for critcl::ccommand and critcl::cproc invokations.

11. Modified packages critcl and critcl::class to provide better function names for (class) method tracing. Bumped package critcl::class to version 1.0.7.

12. Extended the support package critcl::literals with limited configurability. It is now able to generate code for C-level access to the pool without Tcl types (Mode c). The previously existing functionality is accesssible under mode tcl, which also is the default. Both modes can be used together.

13. Extended the support package critcl::emap with limited configurability. It is now able to generate code for C-level access to the mapping without Tcl types (Mode c). The previously existing functionality is accessible under mode tcl, which also is the default. Both modes can be used together.

## Changes for version 3.1.16

1. New feature. Extended critcl::cproc's argument handling to allow arbitrary mixing of required and optional arguments.

2. New feature. Potential Incompatibility.

   Extended critcl::cproc's argument handling to treat an argument args as variadic if it is the last argument of the procedure.

3. New feature. Added two introspection commands, critcl::has-argtype and critcl::has-resulttype. These enable a user to test if a specific (named) type conversion is implemented or not.

4. Added new result type Tcl_Obj*0, with alias object0. The difference to Tcl_Obj* is in the reference counting.

5. Extended the command critcl::argtypesupport with new optional argument through which to explicitly specify the identifier for guarding against multiple definitions.

6. Bugfix: Fixed problem with the implementation of issue #54 (See 3.1.14). Always create the secondary log file. Otherwise end-of-log handling may break, unconditionally assuming its existence.

7. Bugfix: Fixed problem with the internal change to the hook HandleDeclAfterBuild. Corrected the forgotten critcl::cconst.

8. Debugging aid: Added comment holding the name of the result type when emitting result conversions.

9. Bugfix: Fixed issue #60. Unbundled the package directories containing multiple packages. All directories under "lib/" now contain exactly one package.

10. Bugfix: Fixed issue #62, a few dict exists commands operating on a fixed string instead of a variable.

11. Bugfix: Fixed issue #56. Release builders are reminded to run the tests.

12. Bugfix: Fixed issue #55. For FreeBSD critcl's platform package now identifies the Kernel ABI version. Initialization of the cache directory now also uses platform::identify for the default path, instead of platform::generic.

13. Bugfix: Fixed issue #58. Simplified the setup and use of md5. Critcl now makes use of its own package for md5, using itself to built it. There is no chicken/egg problem with this as the -pkg mode used for this does not use md5. That is limited to mode compile & run.

## Changes for version 3.1.15

1. Fixed version number bogosity with 3.1.14.

## Changes for version 3.1.14

1. Fixed issue #36. Added message to target all of the Makefile generated for TEA mode. Additionally tweaked other parts of the output to be less noisy.

2. Accepted request implied in issue #54. Unconditionally save the compiler/linker build log into key log of the dictionary returned by cresults, and save a copy of only the execution output in the new key exl ("execution log").

3. Fixed issue #53. Clarified the documentation of commands critcl::load and critcl::failed with regard to their results and the throwing of errors (does not happen).

4. Fixed issue #48. Modified mode "compile & run" to allow new declarations in a file, after it was build, instead of erroring out. The new decls are build when needed. Mode "precompile" is unchanged and will continue to trap the situation.

5. Fixed issue #52. Updated the local Tcl/Tk headers to 8.4.20, 8.5.13, and 8.6.4.

6. Fixed issue #45. New feature command critcl::cconst.

7. critcl::util: New command locate to find a file across a set of paths, and report an error when not found. This is for use in autoconf-like header-searches and similar configuration tests.

8. Modified 'AbortWhenCalledAfterBuild' to dump the entire stack (info frame!). This should make it easier to determine the location of the troubling declaration.

## Changes for version 3.1.13

1. Merged PR #43. Fixed bug loading adjunct Tcl sources.

2. Fixes in documentation and generated code of package "critcl::enum". Bumped to version 1.0.1.

3. Fixes in documentation of package "critcl::bitmap".

4. New package "critcl::emap". In essence a variant or cross of "critcl::bitmap" with behaviour like "critcl::enum".

5. Merged PR #49. Fixed documentation typo.

6. Merged PR #46. Fixed documentation typo.

7. Merged PR #47. Fixes to test results to match the accumulated code changes. Also made portable across Tcl versions (varying error syntax).

8. New predefined argument- and result-type "wideint" mapping to Tcl_WideInt.

9. New predefined argument-type "bytes" mapping to tuple of byte-array data and length. Note: The existing "bytearray" type (and its aliases) was left untouched, to keep backward compatibility.

10. Modified the internal interface between the Tcl shim and C function underneath "critcl::cproc" with respect to the handling of optional arguments. An optional argument "X" now induces the use of two C arguments, "X" and "has_X". The new argument "has_X" is of boolean (int) type. It is set to true when X is set, and set to false when X has the default value. C code which cares about knowing if the argument is default or not is now able to check that quickly, without having to code the default value inside. NOTE: This change is visible in the output of the advanced commands "argcnames", "argcsignature", "argvardecls", and "argconversion".

11. Fixed issue #50 and documented the availability of variable "interp" (type Tcl_Interp*) within "critcl::cinit" C code fragments. Note that while the old, undocumented name of the variable, "ip", is still usable, it is deprecated. It will be fully removed in two releases, i.e. for release 3.1.15. The variable name was changed to be consistent with other code environments.

12. Fixed issue #51. Disabled the generation of #line directives for "critcl::config lines 0" coming from template files, or code generated with them before the final value of this setting was known.

13. Fixed issue with handling of namespaced package names in "critcl::iassoc". Equivalent to a bug in "critcl::class" fixed for critcl 3.1.1, critcl::class 1.0.1. Note: "literals", "enum", "emap", and "bitmap" do not require a fix as they are all built on top of "iassoc".

## Changes for version 3.1.12

1. Fixed issue 42. Clear ::errorInfo immediately after startup to prevent leakage of irrelevant (caught) errors into our script and confusing the usage code.

2. Fixed issue 40. Keep the order of libraries, and allow duplicates. Both are things which are occasionally required for proper linking.

3. Extended the utility package critcl::literals to declare a cproc result-type for a pool.

   Further fixed the generated header to handle multiple inclusion.

   Bumped version to 1.1.

4. Fixed issue with utility package critcl::bitmap.

   Fixed the generated header to handle multiple inclusion.

   Bumped version to 1.0.1.

5. Created new utility package critcl::enum for the quick and easy setup and use of mappings between C values and Tcl strings. Built on top of critcl::literals.

6. Added examples demonstrating the use of the utility packages critcl::literals, critcl::bitmap, and critcl::enum

## Changes for version 3.1.11

1. Fixed issue #37, via pull request #38, with thanks to Jos DeCoster. Information was stored into the v::delproc and v::clientdata arrays using a different key than when retrieving the same information, thus failing the latter.

2. New convenience command critcl::include for easy inclusion of headers and other C files.

3. New command critcl::make to generate a local header of other C files for use by other parts of a package through inclusion.

4. New utility package critcl::literals for quick and easy setup of and access to pools of fixed Tcl_Obj* strings. Built on top of critcl::iassoc.

5. New utility package critcl::bitmap for quick and easy setup and use of mappings between C bitsets and Tcl lists whose string elements represent that set. Built on top of critcl::iassoc.

## Changes for version 3.1.10

1. Fixed code version numbering forgotten with 3.1.9.

2. Fixed issue #35. In package mode (-pkg) the object cache directory is unique to the process, thus we do not need content-hashing to generate unique file names. A simple counter is sufficient and much faster.

   Note that mode "compile & run" is not as blessed and still uses content-hasing with md5 to ensure unique file names in its per-user object cache.

3. Fixed issue where the ccommand forgot to use its body as input for the UUID generation. Thus ignoring changes to it in mode compile & run, and not rebuilding a library for changed sources. Bug and fix reported by Peter Spjuth.

## Changes for version 3.1.9

1. Fixed issue #27. Added missing platform definitions for various alternate linux and OS X targets.

2. Fixed issue #28. Added missing -mXX flags for linking at the linux-{32,64}-* targets.

3. Fixed issue #29. Replaced the use of raw "cheaders" information in the processing of "cdefines" with the proper include directives derived from it.

4. Fixed the issue behind rejected pull request #30 by Andrew Shadura. Dynamically extract the stubs variable declarations from the Tcl header files and generate matching variable definitions for use in the package code. The generated code will now be always consistent with the headers, even when critcl's own copy of them is replaced by system headers.

5. Fixed issue #31. Accepted patch by Andrew Shadura, with changes (comments), for easier integration of critcl with OS package systems, replacing critcl's copies of Tcl headers with their own.

6. Fixed issue #32. Merged pull request by Andrew Shadura. Various typos in documentation and comments.

7. Fixed issue #34. Handle files starting with a dot better.

## Changes for version 3.1.8

1. Fixed issue with package indices generated for Tcl 8.4. Join the list of commands with semi-colon, not newline.

2. Fixed issue #26 which brought up use-cases I had forgotten to consider while fixing bug #21 (see critcl 3.1.6).

## Changes for version 3.1.7

1. Fixed issue #24. Extract and unconditionally display compiler warnings found in the build log. Prevents users from missing warnings which, while not causing the build to fail, may still indicate problems.

2. New feature. Output hook. All non-messaging user output is now routed through the command critcl::print, and users are allowed to override it when using the critcl application-as-package.

3. New feature, by Ashok P. Nadkarni. Platform configurations can inherit values from configurations defined before them.

## Changes for version 3.1.6

1. Fixed issue #21. While the multi-definition of the stub-table pointer variables was ok with for all the C linkers seen so far C++ linkers did not like this at all. Reworked the code to ensure that this set of variables is generated only once, in the wrapper around all the pieces to assemble.

2. Fixed issue #22, the handling of the command identifier arguments of critcl::ccommand, critcl::cproc, and critcl::cdata. We now properly allow any Tcl identifier and generate proper internal C identifiers from them.

   As part of this the signature of command critcl::name2c changed. The command now delivers a list of four values instead of three. The new value was added at the end.

   Further adapted the implementation of package critcl::class, a user of critcl::name2c. This package is now at version 1.0.6 and requires critcl 3.1.6

   Lastly fixed the mis-handling of option -cname in critcl::ccommand, and critcl::cproc.

3. Fixed issue #23.

## Changes for version 3.1.5

1. Fixed issue #19. Made the regular expression extracting the MSVC version number more general to make it work on german language systems. This may have to be revisited in the future, for other Windows locales.

2. Fixed issue #20. Made option -tea work on windows, at least in a unix emulation environment like msys/mingw.

## Changes for version 3.1.4

1. Bugfix in package critcl::class. Generate a dummy field in the class structure if the class has no class variables. Without this change the structure would be empty, and a number of compilers are not able to handle such a type.

2. Fixed a typo which broke the win64 configuration.

3. Fixed issue #16, a typo in the documentation of command critcl::class.

## Changes for version 3.1.3

1. Enhancement. In detail:

2. Added new argument type "pstring", for "Pascal String", a counted string, i.e. a combination of string pointer and string length.

3. Added new methods critcl::argtypesupport and ::critcl::argsupport to define and use additional supporting code for an argument type, here used by "pstring" above to define the necessary structure.

4. Semi-bugfixes in the packages critcl::class and critcl::iassoc. Pragmas for the AS meta data scanner to ensure that the template files are made part of the package. Versions bumped to 1.0.4 and 1.0.1 respectively.

## Changes for version 3.1.2

1. Enhancement. In detail:

2. Extended critcl::cproc to be able to handle optional arguments, in a limited way. This is automatically available to critcl::class cproc-based methods as well.

3. Bugfix in lassign emulation for Tcl 8.4. Properly set unused variables to the empty string. Bumped version of emulation package lassign84 to 1.0.1.

## Changes for version 3.1.1

1. Bugfixes all around. In detail:

2. Fixed the generation of wrong#args errors for critcl::cproc and derived code (critcl::class cproc-based methods). Use NULL if there are no arguments, and take the offset into account.

3. Fixed the handling of package names by critcl::class. Forgot that they may contain namespace separators. Bumped to version 1.0.1.

4. Extended a critcl::class generated error message in instance creation for clarity. Bumped to version 1.0.2.

## Changes for version 3.1

1. Added a new higher-level package critcl::iassoc.

   This package simplifies the creation of code associating data with an interpreter via Tcl's Tcl_(Get|Set)AssocData() APIs. The user can concentrate on his data while all the necessary boilerplate C code to support this is generated by the package.

   This package uses several of the new features which were added to the core critcl package, see below.

2. Added the higher-level package critcl::class.

   This package simplifies the creation of C level objects with class and instance commands. The user can write a class definition with class- and instance-variables and -methods similar to a TclOO class, with all the necessary boilerplate C code to support this generated by the package.

   This package uses several of the new features which were added to the core critcl package, see below.

3. Extended the API for handling TEApot metadata. Added the command critcl::meta? to query the stored information. Main use currently envisioned is retrieval of the current package's name by utility commands, for use in constructed names. This particular information is always available due to the static scan of the package file on execution of the first critcl command.

   The new packages critcl::iassoc and critcl::class (see above) are users of this command.

4. Extended the API with a command, critcl::name2c, exposing the process of converting a Tcl name into base name, namespace, and C namespace. This enables higher-level code generators to generate the same type of C identifiers as critcl itself.

   The new package critcl::class (see above) is a user of this command.

5. Extended the API with a command, critcl::source, executing critcl commands found in a separate file in the context of the current file. This enables easier management of larger bodies of code as it allows the user to split such up into easier to digest smaller chunks without causing the generation of multiple packages.

6. Related to the previous item, extended the API with commands to divert collection of generated C code into memory. This makes it easier to use the commands for embedded C code in higher-level code generators.

   See the section Advanced: Diversions for details of the provided commands.

   The new package critcl::class (see above) is a user of these facilities.

7. Extended the API with commands helping developers with the generation of proper C #line directives. This allows higher-level code generators to generate and insert their own directives, ensuring that compile errors in their code are properly attributed.

   See the section Advanced: Location management for details of the provided commands.

   The new packages critcl::iassoc and critcl::class (see above) are users of these facilities.

8. Extended the API with commands giving users the ability to define custom argument and result types for ::critcl::cproc.

   See the section Advanced: Extending cproc for details of the provided commands.

## Changes for version 3.0.7

1. Fixed the code generated by critcl::c++command. The emitted code handed a non-static string table to Tcl_GetIndexFromObj, in violation of the contract, which requires the table to have a fixed address. This was a memory smash waiting to happen. Thanks to Brian Griffin for alrerting us to the general problem.

## Changes for version 3.0.6

1. Fixed github issue 10. The critcl application now delivers a proper exit code (1) on build failure, instead of always indicating success (status 0).

2. Fixed github issue 13. Handling of bufferoverflowU.lib for release builds was inconsistent with handling for debug builds. It is now identically handled (conditional) by both cases.

3. Documentation cleanup, mainly in the installation guide, and the README.md shown by github

## Changes for version 3.0.5

1. Fixed bug in the new code for #line pragmas triggered when specifying C code without leading whitespace.

2. Extended the documentation to have manpages for the license, source retrieval, installer, and developer's guides.

## Changes for version 3.0.4

1. Fixed generation of the package's initname when the incoming code is read from stdin and has no proper path.

2. Fixed github issue 11. Now using /LIBPATH instead of -L on Windows (libinclude configuration setting).

3. Extended critcl to handle -l:path format of -l options. GNU ld 2.22+ handles this by searching for the path as is. Good when specifying static libraries, as plain -l looks for shared libraries in preference over static. critcl handles it now, as older GNU ld's do not understand it, nor the various vendor-specific linkers.

4. Fixed github issue #12. Critcl now determines the version of MSVC in use and uses it to switch between various link debug options. Simplified the handling of bufferoverflowU.lib also, making use of the same mechanism and collapsing the two configurations sections we had back into one.

5. Reworked the insertion of #line pragmas into the generated C code to avoid limitations on the line number argument imposed by various compilers, and be more accurate.

6. Modified argument processing. Option -libdir now also implies -L for its argument.

7. Extended handling of option -show (critcl::showconfig) to list the path of the configuration file the data is coming from. Good for debugging configuration processing.

8. Extended the build script with targets to regenerate the embedded documentation, and diagrams, and to generate a release.

## Changes for version 3.0.3

1. Fixed github issues 5 and 8, for the example build.tcl scripts. Working around a missing variable ::errorInfo. It should always be present, however there seem to be revisions of Tcl around which violate this assumption.

## Changes for version 3.0.2

1. Fixed issue in compile-and-run mode where commands put into the auto_index are not found by Tcl's [unknown] command.

2. Fixed an array key mismatch breaking usage of client data and delete function for procedure. Reported by Jos DeCoster, with patch.

3. Implemented a command line option -L, an equivalent of option -I, just for library search paths.

4. Fixed github issues 5 and 8. Working around a missing variable ::errorInfo. It should always be present, however there seem to be revisions of Tcl around which violate this assumption.

## Changes for version 3.0.1

1. Bugfixes all around. In detail:

2. Fixed recording of Tcl version requirements. Keep package name and version together, unbreaking generated meta data and generated package load command.

3. Fixed the build scripts: When installing, or wrapping for TEA, generate any missing directories

4. Modified the build scripts to properly exit the application when the window of their GUI is closed through the (X) button.

5. Removed an 8.5-ism (open wb) which had slipped into the main build script.

6. Modified the example build scripts to separate the output for the different examples (and packages) by adding empty lines.

7. stack::c example bugfix: Include API declarations for use in the companion files.

8. Extended the documentation: Noted the need for a working installation of a C compiler.

9. Extended the Windows target definitions and code to handle the manifest files used by modern MS development environments. Note that this code handles both possibilities, environment using manifests, and (old(er)) environments without.

10. Extended the Windows 64bit target definitions and code to auto-detect the need for the helper library "bufferoverflowU.lib" and reconfigure the compile and link commands appropriately. We assume that the library must be linked when present. This should be no harm if the library is present, yet not needed. Just superfluous. We search for the library in the paths specified by the environment variable LIB.

## Changes for version 3

1. The command critcl::platform was deprecated in version 2.1, superceded by critcl::targetplatform, yet kept for compatibility. Now it has been removed.

2. The command critcl::compiled was kept with in version 2.1 with semantics in contradiction to its, for compatibility. This contradiction has been removed, changing the visible semantics of the command to be in line with its name.

3. The change to version 3 became necessary because of the two incompatible visible changes above.

4. Extended the application package with code handling a new option -tea. Specifying this option invokes a special mode where critcl generates a TEA package, i.e. wraps the input into a directory hierarchy and support files which provide it TEA-lookalike buildsystem.

   This new option, and -pkg, exclude each other. If both are specified the last used option takes precedence.

   The generated package directory hierarchy is mostly self-contained, but not fully. It requires not only a working installation of Tcl, but also working installations of the packages md5 and cmdline. Both of these are provided by the Tcllib bundle. Not required, but recommended to have installed are any of the packages which can accelerate md5's operation, i.e. cryptkit, tcllibc, or Trf.

5. Extended the critcl package with a new command critcl::scan taking the path to a ".critcl" file, statically scanning it, and returning license, version, a list of its companion files, list of imported APIs, and list of developer-specified custom configuration options. This data is the foundation for the TEA wrapping described above.

   Note that this is a static scan. While the other build modes can (must) execute the ".critcl" file and make platform-specific decisions regarding the assembled C code, companion files, etc. the TEA wrap mode is not in a position to make platform-specific decisions. It has to wrap everything which might conceivably be needed when actually building. Hence the static scan. This has however its own set of problems, namely the inability to figure out any dynamic construction of companion file paths, at least on its own. Thus:

6. Extended the API used by critcl-based packages with the command critcl::owns. While this command is ignored by the regular build modes the static scanner described above takes its arguments as the names of companion files which have to be wrapped into the TEA package and could not be figured by the scanner otherwise, like because of dynamic paths to critcl::tsources, critcl::csources, getting sourced directly, or simply being adjunct datafiles.

7. Extended the API used by critcl-based packages with the command critcl::api for the management of stubs tables, be it their use, and/or declaration and export.

   Please see section Stubs Table Management of the critcl package documentation for details.

8. Extended the API used by critcl-based packages with the command critcl::userconfig for the management of developer-specified custom configuration options, be it their use and/or declaration.

   Please see section Custom Build Configuration of the critcl package documentation for details.

9. Extended the API used by critcl-based packages with the commands critcl::description, critcl::summary, critcl::subject, critcl::meta, and critcl::buildrequirement for the declaration of TEApot meta data for/about the package.

   Please see section Package Meta Data of the critcl package documentation for details.

## Changes for version 2.1

1. Fixed bug where critcl::tsources interpreted relative paths as relative to the current working directory instead of relative to the ".critcl" file using the command, as all other commands of this type do.

2. Fixed internals, preventing information collected for multiple ".critcl" files to leak between them. Notably, critcl::tk is not a global configuration option anymore.

3. Fixed the command critcl::license to be a null-operation in mode "compile & run", instead of throwing an error.

4. Fixed the critcl application's interference with the "compile & run" result cache in -pkg mode by having it use a wholly separate (and by default transient) directory for that mode.

5. Fixed bug where changes to a ".critcl" file did not result in a rebuild for mode "compile & run". All relevant API commands now ensure UUID changes.

6. Fixed bug in the backend handling of critcl::debug where the companion c-sources of a ".critcl" file were not compiled with debug options, although the ".critcl" file was.

7. Fixed bug in critcl::debug which prevented recognition of mode "all" when it was not the first argument to the command.

8. Fixed bug in "preload.c" preventing its compilation on non-windows platforms.

9. Fixed long-standing bug in the handling of namespace qualifiers in the command name argument of critcl::cproc and critcl::ccommand. It is now possible to specify a fully qualified command name without issues.

10. Extended/reworked critcl::tsources to be the canonical way of declaring ".tcl" companion files even for mode "compile & run".

11. Extended/reworked critcl::tsources to allow the use of a ".critcl" file as its own Tcl companion file.

12. Extended critcl::framework to internally check for OS X build target, and to ignore the declaration if its not.

13. Extended critcl::failed to be callable more than once in a ".critcl" file. The first call forces the build, if it was not done already, to get the result. Further calls return the cached result of the first call.

14. Extended the handling of environment variable CC in the code determining the compiler to use to deal with (i.e. remove) paths to the compiler, compiler file extensions, and compiler options specified after the compiler itself, leaving only the bare name of the compiler.

15. Extended the code handling the search for preloaded libraries to print the paths it searched, making debugging of a search failure easier.

16. A new command critcl::tcl can be used to declare the version of Tcl minimally needed to build and run the ".critcl" file and package. Defaults to 8.4 if not declared. Extended critcl to have the stubs and headers for all of Tcl 8.4, 8.5, and 8.6.

17. A new command critcl::load forces the build and load of a ".critcl" file. This is the official way for overriding critcl's default lazy-build-&-load-on-demand scheme for mode "compile & run".

    Note that after using critcl::load / critcl::failed in a ".critcl" file it is not possible to use critcl commands in that file anymore. Doing so will throw an error.

18. Extended the generation of '#line' pragmas to use info frame (if available) to provide the C compiler with exact line numbers into the ".critcl" file for the reporting of warnings and errors.

19. Extended critcl::check with logging to help with debugging build-time checks of the environment, plus an additional optional argument to provide labeling.

20. Added a new command critcl::checklink which not only tries to check the environment via compiling the code, but also its linkability.

21. Added a new command critcl::msg for messaging, like command critcl::error is for error reporting. Likewise this is a hook a user of the package is allowed to override. The default implementation, used by mode compile & run does nothing. The implementation for mode generate package prints the message to stdout.

    Envisioned use is for the reporting of results determined by critcl::check and critcl::checklink during building, to help with debugging when something goes wrong with a check.

22. Exposed the argument processing internals of critcl::proc for use by advanced users. The new commands are

    1. critcl::argnames

    2. critcl::argcnames

    3. critcl::argcsignature

    4. critcl::argvardecls

    5. critcl::argconversion

    Please see section Advanced Embedded C Code of the critcl package documentation for details.

23. Extended the critcl package to intercept package provide and record the file -> package name mapping. Plus other internal changes now allow the use of namespaced package names while still using proper path names and init function.

24. Dropped the unused commands critcl::optimize and critcl::include.

25. Dropped -lib mode from the critcl application.

26. Dropped remnants of support for Tcl 8.3 and before.

## Authors

Jean Claude Wippler, Steve Landers, Andreas Kupries

## Bugs, Ideas, Feedback

This document, and the package it describes, will undoubtedly contain bugs and other problems. Please report them at https://github.com/andreas-kupries/critcl/issues. Ideas for enhancements you may have for either package, application, and/or the documentation are also very welcome and should be reported at https://github.com/andreas-kupries/critcl/issues as well.

## Keywords

C code, Embedded C Code, code generator, compile & run, compiler, dynamic code generation, dynamic compilation, generate package, linker, on demand compilation, on-the-fly compilation

## Category

Glueing/Embedded C code

## Copyright

Copyright © Jean-Claude Wippler
Copyright © Steve Landers
Copyright © 2011-2015 Andreas Kupries