Libbonobo Reference Manual | ||||
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Top | Description |
bonobo-event-sourcebonobo-event-source — An Event Source where clients can connect to listen to events. |
Synopsis
BonoboEventSource * bonobo_event_source_new (void
); void bonobo_event_source_notify_listeners (BonoboEventSource *event_source
,const char *event_name
,const CORBA_any *opt_value
,CORBA_Environment *opt_ev
); void bonobo_event_source_notify_listeners_full (BonoboEventSource *event_source
,const char *path
,const char *type
,const char *subtype
,const CORBA_any *opt_value
,CORBA_Environment *opt_ev
); void bonobo_event_source_client_remove_listener (Bonobo_Unknown object
,Bonobo_Listener listener
,CORBA_Environment *opt_ev
); void bonobo_event_source_client_add_listener (Bonobo_Unknown object
,BonoboListenerCallbackFn event_callback
,const char *opt_mask
,CORBA_Environment *opt_ev
,gpointer user_data
); gboolean bonobo_event_source_has_listener (BonoboEventSource *event_source
,const char *event_name
); void bonobo_event_source_client_add_listener_closure (Bonobo_Unknown object
,GClosure *callback
,const char *opt_mask
,CORBA_Environment *opt_ev
); Bonobo_Listener bonobo_event_source_client_add_listener_full (Bonobo_Unknown object
,GClosure *callback
,const char *opt_mask
,CORBA_Environment *opt_ev
); void bonobo_event_source_ignore_listeners (BonoboEventSource *event_source
);
Description
An event source object is responsible for channeling the emission of signals on an object to the appropriate attached listeners. The API is extremely simple and allows implementations to notify their listeners of a new event occuring.
To notify a listener, you need to construct a textual string,
this is done by the bonobo_event
functions
( see BonoboListener ) ':' delimiting the fields. It is reccommended
that the IDL module path of the interface be used as the first
part of the string. This is because many interfaces can be aggregated
together and need to share the same event namespace without conflicts.
So for example the bonobo property bag notification code
uses the IDL path "Bonobo/Property" the "change" kind and sets the
sub-type to the property name:
Example 9. An example event source notification
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static void notify_listeners (BonoboPropertyBag *pb, BonoboProperty *prop, const BonoboArg *new_value, CORBA_Environment *opt_ev) { if (prop->flags & BONOBO_PROPERTY_NO_LISTENING) return; bonobo_event_source_notify_listeners_full (pb->es, "Bonobo/Property", "change", prop->name, new_value, opt_ev); } |
Of course, you need to notify the listener with a valid
BonoboArg containing the event data, this could easily contain
a structure. eg.
Example 10. Passing a structure in an event
module GNOME { module Foo { struct BaaEvent { double a; string b; long c; }; }; };
static void fire_event (BonoboEventSource *on_source, double a_double, char *a_string, long a_float, CORBA_Environment *opt_ev) { CORBA_any any; GNOME_Foo_BaaEvent e; e.a = a_double; e.b = a_string; e.c = a_float; any->_type = TC_GNOME_Foo_BaaEvent; any->_data = &e; bonobo_event_source_notify_listeners_full ( on_source, "GNOME/Foo", "event", NULL, &any, opt_ev); }
NB. it is reccommended that you make it clear that the event
structure is intended for use with the BonoboEventSource /
BonoboListener by naming it XYZEvent, ie. with the 'Event'
suffix.
Details
bonobo_event_source_new ()
BonoboEventSource * bonobo_event_source_new (void
);
Creates a new BonoboEventSource object. Typically this object will be exposed to clients through CORBA and they will register and unregister functions to be notified of events that this EventSource generates.
To notify clients of an event, use the bonobo_event_source_notify_listeners()
function.
Returns : |
A new BonoboEventSource server object. |
bonobo_event_source_notify_listeners ()
void bonobo_event_source_notify_listeners (BonoboEventSource *event_source
,const char *event_name
,const CORBA_any *opt_value
,CORBA_Environment *opt_ev
);
This will notify all clients that have registered with this EventSource
(through the addListener or addListenerWithMask methods) of the availability
of the event named event_name
. The value
CORBA::any value is passed to
all listeners.
event_name
can not contain comma separators, as commas are used to
separate the various event names.
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the Event Source that will emit the event. |
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Name of the event being emitted |
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A CORBA_any value that contains the data that is passed to interested clients, or NULL for an empty value |
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A CORBA_Environment where a failure code can be returned, can be NULL. |
bonobo_event_source_notify_listeners_full ()
void bonobo_event_source_notify_listeners_full (BonoboEventSource *event_source
,const char *path
,const char *type
,const char *subtype
,const CORBA_any *opt_value
,CORBA_Environment *opt_ev
);
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bonobo_event_source_client_remove_listener ()
void bonobo_event_source_client_remove_listener (Bonobo_Unknown object
,Bonobo_Listener listener
,CORBA_Environment *opt_ev
);
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bonobo_event_source_client_add_listener ()
void bonobo_event_source_client_add_listener (Bonobo_Unknown object
,BonoboListenerCallbackFn event_callback
,const char *opt_mask
,CORBA_Environment *opt_ev
,gpointer user_data
);
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bonobo_event_source_has_listener ()
gboolean bonobo_event_source_has_listener (BonoboEventSource *event_source
,const char *event_name
);
This method determines if there are any listeners for the event to be broadcast. This can be used to detect whether it is worth constructing a potentialy expensive state update, before sending it to no-one.
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the Event Source that will emit the event. |
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Name of the event being emitted |
Returns : |
TRUE if it's worth sending, else FALSE |
bonobo_event_source_client_add_listener_closure ()
void bonobo_event_source_client_add_listener_closure (Bonobo_Unknown object
,GClosure *callback
,const char *opt_mask
,CORBA_Environment *opt_ev
);
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bonobo_event_source_client_add_listener_full ()
Bonobo_Listener bonobo_event_source_client_add_listener_full (Bonobo_Unknown object
,GClosure *callback
,const char *opt_mask
,CORBA_Environment *opt_ev
);
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Returns : |