## gnome-triggers

gnome-triggers — Hierarchical signal mechanism for GNOME events.

## Synopsis

    #include <libgnome/libgnome.h>

    enum                GnomeTriggerType;
    void                (*GnomeTriggerActionFunction)       (char *msg,
                                                             char *level,
                                                             char *supinfo[]);

## Description

The triggers API provides a way for applications to tell GNOME about interesting events that then cause something to happen (for example, playing a sound). An event can either be a function that is called, a sound that is played or an external command that is run.

Each trigger can optionally have a level associated with it and a section. The section is a list of strings that help to classify the event, which imposes a hierarchy on the trigger system. For example, messages about the hard drive partition /dev/hda1 may come under the section ("system", "device", "disk", "/dev/hda1"). This means that an application could trigger all events for the ("system", "device") sections and include those events, or be more specific and just trigger those for ("system", "device", "disk", "/dev/hda1").

At the present time, triggers are not widely used in GNOME, being mostly used to play sound events in response to certain actions.

## Details

### enum GnomeTriggerType

    typedef enum {
    	GTRIG_NONE,
    	GTRIG_FUNCTION,
    	GTRIG_COMMAND,
    	GTRIG_MEDIAPLAY
    } GnomeTriggerType;

These are the different types of triggers that can be activated by an application.

`GTRIG_NONE` | A null trigger type. Should never be used.
`GTRIG_FUNCTION` | The trigger causes a function to be executed.
`GTRIG_COMMAND` | The trigger causes a command to be executed (using `execv()`).
`GTRIG_MEDIAPLAY` | The trigger causes a sound to be played.

### GnomeTriggerActionFunction ()

    void                (*GnomeTriggerActionFunction)       (char *msg,
                                                             char *level,
                                                             char *supinfo[]);

The signature of a function that can used as a target for GTRIG_FUNCTION types of GnomeTrigger instances.

`msg` : | The human-readable message that was passed to `gnome_triggers_do()`. May be `NULL`.
`level` : | The severity level of the event. May be `NULL`.
`supinfo` : | The section in which the event belongs. This is a `NULL` terminated array.