gedit Reference Manual: GeditMessageBus

## GeditMessageBus GeditMessageBus — internal message communication bus |

## Functions

void | (*GeditMessageCallback) ()
GeditMessageBus * | gedit_message_bus_get_default ()
GeditMessageBus * | gedit_message_bus_new ()
GType | gedit_message_bus_lookup ()
void | gedit_message_bus_register ()
void | gedit_message_bus_unregister ()
void | gedit_message_bus_unregister_all ()
gboolean | gedit_message_bus_is_registered ()
void | gedit_message_bus_foreach ()
guint | gedit_message_bus_connect ()
void | gedit_message_bus_disconnect ()
void | gedit_message_bus_disconnect_by_func ()
void | gedit_message_bus_block ()
void | gedit_message_bus_block_by_func ()
void | gedit_message_bus_unblock ()
void | gedit_message_bus_unblock_by_func ()
void | gedit_message_bus_send_message ()
void | gedit_message_bus_send_message_sync ()
void | gedit_message_bus_send ()
GeditMessage * | gedit_message_bus_send_sync ()

## Signals

void | dispatch | Run Last
void | registered | Run Last
void | unregistered | Run Last

## Types and Values

struct | GeditMessageBus

## Object Hierarchy

        GObject
        ╰── GeditMessageBus

## Includes

    #include <gedit/gedit-message-bus.h>

## Description

gedit has a communication bus very similar to DBus. Its primary use is to allow easy communication between plugins, but it can also be used to expose gedit functionality to external applications by providing DBus bindings for the internal gedit message bus.

There are two different communication busses available. The default bus (see `gedit_message_bus_get_default()`) is an application wide communication bus. In addition, each GeditWindow has a separate, private bus (see `gedit_window_get_message_bus()`). This makes it easier for plugins to communicate to other plugins in the same window.

The concept of the message bus is very simple. You can register a message type on the bus, specified as a Method at a specific Object Path with a certain set of Method Arguments. You can then connect callback functions for this message type on the bus. Whenever a message with the Object Path and Method for which callbacks are connected is sent over the bus, the callbacks are called. There is no distinction between Methods and Signals (signals are simply messages where sender and receiver have switched places).

Example 1. Registering a message type

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    GeditMessageBus *bus = gedit_message_bus_get_default ();

    // Register 'method' at '/plugins/example' with one required
    // string argument 'arg1'
    gedit_message_bus_register (bus, EXAMPLE_TYPE_METHOD_MESSAGE,
                                "/plugins/example", "method");

Example 2. Connecting a callback

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    static void
    example_method_cb (GeditMessageBus *bus,
                       GeditMessage    *message,
                       gpointer         user_data)
    {
        gchar *arg1 = NULL;

        gedit_message_get (message, "arg1", &arg1, NULL);
        g_message ("Evoked /plugins/example.method with: %s", arg1);
        g_free (arg1);
    }

    GeditMessageBus *bus = gedit_message_bus_get_default ();

    guint id = gedit_message_bus_connect (bus,
                                          "/plugins/example", "method",
                                          example_method_cb,
                                          NULL,
                                          NULL);

Example 3. Sending a message

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    GeditMessageBus *bus = gedit_message_bus_get_default ();

    gedit_message_bus_send (bus,
                            "/plugins/example", "method",
                            "arg1", "Hello World",
                            NULL);

## Functions

### GeditMessageCallback ()

    void
    (*GeditMessageCallback) (GeditMessageBus *bus,
                             GeditMessage *message,
                             gpointer user_data);

Callback signature used for connecting callback functions to be called when a message is received (see `gedit_message_bus_connect()`).

#### Parameters

bus | the GeditMessageBus on which the message was sent |
message | the GeditMessage which was sent |
user_data | the supplied user data when connecting the callback |

### gedit_message_bus_get_default ()

    GeditMessageBus *
    gedit_message_bus_get_default (void);

Get the default application GeditMessageBus.

#### Returns

the default GeditMessageBus.

[transfer none]

### gedit_message_bus_new ()

    GeditMessageBus *
    gedit_message_bus_new (void);

Create a new message bus. Use `gedit_message_bus_get_default()` to get the default, application wide, message bus. Creating a new bus is useful for associating a specific bus with for instance a GeditWindow.

#### Returns

a new GeditMessageBus

### gedit_message_bus_lookup ()

    GType
    gedit_message_bus_lookup (GeditMessageBus *bus,
                              const gchar *object_path,
                              const gchar *method);

Get the registered GeditMessageType for `method` at `object_path` . The returned GeditMessageType is owned by the bus and should not be unreffed.

#### Parameters

bus | a GeditMessageBus |
object_path | the object path |
method | the method |

#### Returns

the registered GeditMessageType or `NULL` if no message type is registered for `method` at `object_path`

### gedit_message_bus_register ()

    void
    gedit_message_bus_register (GeditMessageBus *bus,
                                GType message_type,
                                const gchar *object_path,
                                const gchar *method);

Register a message on the bus. A message must be registered on the bus before it can be send. This function registers the type for `method` at `object_path` .

This function emits a “registered” signal.

#### Parameters

bus | a GeditMessageBus |
message_type | the message type |
object_path | the object path |
method | the method to register |

### gedit_message_bus_unregister ()

    void
    gedit_message_bus_unregister (GeditMessageBus *bus,
                                  const gchar *object_path,
                                  const gchar *method);

Unregisters a previously registered message type. This is especially useful for plugins which should unregister message types when they are deactivated.

This function emits the “unregistered” signal.

#### Parameters

bus | a GeditMessageBus |
object_path | the object path |
method | the method |

### gedit_message_bus_unregister_all ()

    void
    gedit_message_bus_unregister_all (GeditMessageBus *bus,
                                      const gchar *object_path);

Unregisters all message types for `object_path` . This is especially useful for plugins which should unregister message types when they are deactivated.

This function emits the “unregistered” signal for all unregistered message types.

#### Parameters

bus | a GeditMessageBus |
object_path | the object path |

### gedit_message_bus_is_registered ()

    gboolean
    gedit_message_bus_is_registered (GeditMessageBus *bus,
                                     const gchar *object_path,
                                     const gchar *method);

Check whether a message type `method` at `object_path` is registered on the bus.

#### Parameters

bus | a GeditMessageBus |
object_path | the object path |
method | the method |

#### Returns

`TRUE` if the `method` at `object_path` is a registered message type on the bus

### gedit_message_bus_foreach ()

    void
    gedit_message_bus_foreach (GeditMessageBus *bus,
                               GeditMessageBusForeach func,
                               gpointer user_data);

Calls `func` for each message type registered on the bus

#### Parameters

bus | the GeditMessagebus |
func | the callback function. | [scope call]
user_data | the user data to supply to the callback function |

### gedit_message_bus_connect ()

    guint
    gedit_message_bus_connect (GeditMessageBus *bus,
                               const gchar *object_path,
                               const gchar *method,
                               GeditMessageCallback callback,
                               gpointer user_data,
                               GDestroyNotify destroy_data);

Connect a callback handler to be evoked when message `method` at `object_path` is sent over the bus.

#### Parameters

bus | a GeditMessageBus |
object_path | the object path |
method | the method |
callback | function to be called when message `method` at `object_path` is sent |
user_data | user_data to use for the callback. | [allow-none]
destroy_data | function to evoke with `user_data` as argument when `user_data` needs to be freed. | [allow-none]

#### Returns

the callback identifier

### gedit_message_bus_disconnect ()

    void
    gedit_message_bus_disconnect (GeditMessageBus *bus,
                                  guint id);

Disconnects a previously connected message callback.

#### Parameters

bus | a GeditMessageBus |
id | the callback id as returned by `gedit_message_bus_connect()` |

### gedit_message_bus_disconnect_by_func ()

    void
    gedit_message_bus_disconnect_by_func (GeditMessageBus *bus,
                                          const gchar *object_path,
                                          const gchar *method,
                                          GeditMessageCallback callback,
                                          gpointer user_data);

Disconnects a previously connected message callback by matching the provided callback function and user_data. See also `gedit_message_bus_disconnect()`.

#### Parameters

bus | a GeditMessageBus |
object_path | the object path |
method | the method |
callback | the connected callback. | [scope call]
user_data | the user_data with which the callback was connected |

### gedit_message_bus_block ()

    void
    gedit_message_bus_block (GeditMessageBus *bus,
                             guint id);

Blocks evoking the callback specified by `id` . Unblock the callback by using `gedit_message_bus_unblock()`.

#### Parameters

bus | a GeditMessageBus |
id | the callback id |

### gedit_message_bus_block_by_func ()

    void
    gedit_message_bus_block_by_func (GeditMessageBus *bus,
                                     const gchar *object_path,
                                     const gchar *method,
                                     GeditMessageCallback callback,
                                     gpointer user_data);

Blocks evoking the callback that matches provided `callback` and `user_data` . Unblock the callback using `gedit_message_unblock_by_func()`.

#### Parameters

bus | a GeditMessageBus |
object_path | the object path |
method | the method |
callback | the callback to block. | [scope call]
user_data | the user_data with which the callback was connected |

### gedit_message_bus_unblock ()

    void
    gedit_message_bus_unblock (GeditMessageBus *bus,
                               guint id);

Unblocks the callback specified by `id` .

#### Parameters

bus | a GeditMessageBus |
id | the callback id |

### gedit_message_bus_unblock_by_func ()

    void
    gedit_message_bus_unblock_by_func (GeditMessageBus *bus,
                                       const gchar *object_path,
                                       const gchar *method,
                                       GeditMessageCallback callback,
                                       gpointer user_data);

Unblocks the callback that matches provided `callback` and `user_data` .

#### Parameters

bus | a GeditMessageBus |
object_path | the object path |
method | the method |
callback | the callback to block. | [scope call]
user_data | the user_data with which the callback was connected |

### gedit_message_bus_send_message ()

    void
    gedit_message_bus_send_message (GeditMessageBus *bus,
                                    GeditMessage *message);

This sends the provided `message` asynchronously over the bus. To send a message synchronously, use `gedit_message_bus_send_message_sync()`. The convenience function `gedit_message_bus_send()` can be used to easily send a message without constructing the message object explicitly first.

#### Parameters

bus | a GeditMessageBus |
message | the message to send |

### gedit_message_bus_send_message_sync ()

    void
    gedit_message_bus_send_message_sync (GeditMessageBus *bus,
                                         GeditMessage *message);

This sends the provided `message` synchronously over the bus. To send a message asynchronously, use `gedit_message_bus_send_message()`. The convenience function `gedit_message_bus_send_sync()` can be used to easily send a message without constructing the message object explicitly first.

#### Parameters

bus | a GeditMessageBus |
message | the message to send |

### gedit_message_bus_send ()

    void
    gedit_message_bus_send (GeditMessageBus *bus,
                            const gchar *object_path,
                            const gchar *method,
                            const gchar *first_property,
                            ...);

This provides a convenient way to quickly send a message `method` at `object_path` asynchronously over the bus. The variable argument list specifies key (string) value pairs used to construct the message arguments. To send a message synchronously use `gedit_message_bus_send_sync()`.

#### Parameters

bus | a GeditMessageBus |
object_path | the object path |
method | the method |
first_property | the first property |
... | NULL terminated list of key/value pairs |

### gedit_message_bus_send_sync ()

    GeditMessage *
    gedit_message_bus_send_sync (GeditMessageBus *bus,
                                 const gchar *object_path,
                                 const gchar *method,
                                 const gchar *first_property,
                                 ...);

This provides a convenient way to quickly send a message `method` at `object_path` synchronously over the bus. The variable argument list specifies key (string) value pairs used to construct the message arguments. To send a message asynchronously use `gedit_message_bus_send()`.

#### Parameters

bus | a GeditMessageBus |
object_path | the object path |
method | the method |
first_property | the first property |
... | `NULL` terminated list of key/value pairs. | [allow-none]

#### Returns

the constructed GeditMessage. The caller owns a reference to the GeditMessage and should call `g_object_unref()` when it is no longer needed.

[allow-none][transfer full]

## Types and Values

### struct GeditMessageBus

    struct GeditMessageBus;

## Signal Details

### The `“dispatch”` signal

    void
    user_function (GeditMessageBus *bus,
                   GeditMessage    *message,
                   gpointer         user_data)

The "dispatch" signal is emitted when a message is to be dispatched. The message is dispatched in the default handler of this signal. Primary use of this signal is to customize the dispatch of a message (for instance to automatically dispatch all messages over DBus).

#### Parameters

bus | a GeditMessageBus |
message | the GeditMessage to dispatch |
user_data | user data set when the signal handler was connected. |

Flags: Run Last

### The `“registered”` signal

    void
    user_function (GeditMessageBus *bus,
                   gchar           *object_path,
                   gchar           *method,
                   gpointer         user_data)

The "registered" signal is emitted when a message has been registered on the bus.

#### Parameters

bus | a GeditMessageBus |
object_path | the registered object path. |
method | the registered method |
user_data | user data set when the signal handler was connected. |

Flags: Run Last

### The `“unregistered”` signal

    void
    user_function (GeditMessageBus *bus,
                   gchar           *object_path,
                   gchar           *method,
                   gpointer         user_data)

The "unregistered" signal is emitted when a message has been unregistered from the bus.

#### Parameters

bus | a GeditMessageBus |
object_path | the unregistered object path. |
method | the unregistered method |
user_data | user data set when the signal handler was connected. |

Flags: Run Last