gclosure.sgml

This GLib version 2.16.1. GLib is the low-level core library that forms the basis for projects such

MyClosure *my_closure_new (gpointer data)
{
  GClosure *closure;
  MyClosure *my_closure;
  
  closure = g_closure_new_simple (sizeof (MyClosure), data);
  my_closure = (MyClosure *) closure;

  / initialize extra data here */

  g_closure_add_finalize_notifier (closure, notify_data,
                                   my_closure_finalize);
  return my_closure;
}
</programlisting>
</informalexample>

@sizeof_closure: the size of the structure to allocate, must be at least 
<literal>sizeof (GClosure)</literal>
@data: data to store in the @data field of the newly allocated #GClosure
@Returns: a newly allocated #GClosure


<!-- ##### FUNCTION g_closure_set_marshal ##### -->
<para>
Sets the marshaller of @closure. The <literal>marshal_data</literal>
of @marshal provides a way for a meta marshaller to provide additional
information to the marshaller. (See g_closure_set_meta_marshal().) For
GObject's C predefined marshallers (the g_cclosure_marshal_*()
functions), what it provides is a callback function to use instead of
@closure->callback.
</para>

@closure: a #GClosure
@marshal: a #GClosureMarshal function


<!-- ##### FUNCTION g_closure_add_marshal_guards ##### -->
<para>
Adds a pair of notifiers which get invoked before and after the closure 
callback, respectively. This is typically used to protect the extra arguments
for the duration of the callback. See g_object_watch_closure() for an
example of marshal guards.
</para>

@closure: a #GClosure
@pre_marshal_data: data to pass to @pre_marshal_notify
@pre_marshal_notify: a function to call before the closure callback
@post_marshal_data: data to pass to @post_marshal_notify
@post_marshal_notify: a function to call after the closure callback


<!-- ##### FUNCTION g_closure_set_meta_marshal ##### -->
<para>
Sets the meta marshaller of @closure. 
A meta marshaller wraps @closure->marshal and modifies the way it is called 
in some fashion. The most common use of this facility is for C callbacks. 
The same marshallers (generated by 
<link linkend="glib-genmarshal">glib-genmarshal</link>) are used everywhere,
but the way that we get the callback function differs. In most cases we want 
to use @closure->callback, but in other cases we want to use some 
different technique to retrieve the callback function.
</para>
<para>
For example, class closures for signals (see g_signal_type_cclosure_new()) 
retrieve the callback function from a fixed offset in the class structure. 
The meta marshaller retrieves the right callback and passes it to the 
marshaller as the @marshal_data argument.
</para>

@closure: a #GClosure
@marshal_data: context-dependent data to pass to @meta_marshal
@meta_marshal: a #GClosureMarshal function


<!-- ##### FUNCTION g_source_set_closure ##### -->
<para>
Set the callback for a source as a #GClosure.
</para>
<para>
If the source is not one of the standard GLib types, the @closure_callback
and @closure_marshal fields of the #GSourceFuncs structure must have been
filled in with pointers to appropriate functions.
</para>

@source: the source
@closure: a #GClosure


<!-- ##### MACRO G_TYPE_IO_CHANNEL ##### -->
<para>
The #GType for #GIOChannel.
</para>



<!-- ##### MACRO G_TYPE_IO_CONDITION ##### -->
<para>
The #GType for #GIOCondition.
</para>



<!-- ##### FUNCTION g_cclosure_marshal_VOID__VOID ##### -->
<para>
A marshaller for a #GCClosure with a callback of type
<literal>void (*callback) (gpointer instance, gpointer user_data)</literal>.
</para>

@closure: the #GClosure to which the marshaller belongs
@return_value: ignored
@n_param_values: 1
@param_values: a #GValue array holding only the instance
@invocation_hint: the invocation hint given as the the last argument
  to g_closure_invoke()
@marshal_data: additional data specified when registering the marshaller


<!-- ##### FUNCTION g_cclosure_marshal_VOID__BOOLEAN ##### -->
<para>
A marshaller for a #GCClosure with a callback of type
<literal>void (*callback) (gpointer instance, gboolean arg1, gpointer user_data)</literal>.
</para>

@closure: the #GClosure to which the marshaller belongs
@return_value: ignored
@n_param_values: 2
@param_values: a #GValue array holding the instance and the #gboolean parameter
@invocation_hint: the invocation hint given as the the last argument
  to g_closure_invoke()
@marshal_data: additional data specified when registering the marshaller


<!-- ##### FUNCTION g_cclosure_marshal_VOID__CHAR ##### -->
<para>
A marshaller for a #GCClosure with a callback of type
<literal>void (*callback) (gpointer instance, gchar arg1, gpointer user_data)</literal>.
</para>

@closure: the #GClosure to which the marshaller belongs
@return_value: ignored
@n_param_values: 2
@param_values: a #GValue array holding the instance and the #gchar parameter
@invocation_hint: the invocation hint given as the the last argument
  to g_closure_invoke()
@marshal_data: additional data specified when registering the marshaller


<!-- ##### FUNCTION g_cclosure_marshal_VOID__UCHAR ##### -->
<para>
A marshaller for a #GCClosure with a callback of type
<literal>void (*callback) (gpointer instance, guchar arg1, gpointer user_data)</literal>.
</para>

@closure: the #GClosure to which the marshaller belongs
@return_value: ignored
@n_param_values: 2
@param_values: a #GValue array holding the instance and the #guchar parameter
@invocation_hint: the invocation hint given as the the last argument
  to g_closure_invoke()
@marshal_data: additional data specified when registering the marshaller


<!-- ##### FUNCTION g_cclosure_marshal_VOID__INT ##### -->
<para>
A marshaller for a #GCClosure with a callback of type
<literal>void (*callback) (gpointer instance, gint arg1, gpointer user_data)</literal>.
</para>

@closure: the #GClosure to which the marshaller belongs
@return_value: ignored
@n_param_values: 2
@param_values: a #GValue array holding the instance and the #gint parameter
@invocation_hint: the invocation hint given as the the last argument
  to g_closure_invoke()
@marshal_data: additional data specified when registering the marshaller


<!-- ##### FUNCTION g_cclosure_marshal_VOID__UINT ##### -->
<para>
A marshaller for a #GCClosure with a callback of type
<literal>void (*callback) (gpointer instance, guint arg1, gpointer user_data)</literal>.
</para>

@closure: the #GClosure to which the marshaller belongs
@return_value: ignored
@n_param_values: 2
@param_values: a #GValue array holding the instance and the #guint parameter
@invocation_hint: the invocation hint given as the the last argument
  to g_closure_invoke()
@marshal_data: additional data specified when registering the marshaller


<!-- ##### FUNCTION g_cclosure_marshal_VOID__LONG ##### -->
<para>
A marshaller for a #GCClosure with a callback of type
<literal>void (*callback) (gpointer instance, glong arg1, gpointer user_data)</literal>.
</para>

@closure: the #GClosure to which the marshaller belongs
@return_value: ignored
@n_param_values: 2
@param_values: a #GValue array holding the instance and the #glong parameter
@invocation_hint: the invocation hint given as the the last argument
  to g_closure_invoke()
@marshal_data: additional data specified when registering the marshaller


<!-- ##### FUNCTION g_cclosure_marshal_VOID__ULONG ##### -->
<para>
A marshaller for a #GCClosure with a callback of type
<literal>void (*callback) (gpointer instance, gulong arg1, gpointer user_data)</literal>.
</para>

@closure: the #GClosure to which the marshaller belongs
@return_value: ignored
@n_param_values: 2
@param_values: a #GValue array holding the instance and the #gulong parameter
@invocation_hint: the invocation hint given as the the last argument
  to g_closure_invoke()
@marshal_data: additional data specified when registering the marshaller


<!-- ##### FUNCTION g_cclosure_marshal_VOID__ENUM ##### -->
<para>
A marshaller for a #GCClosure with a callback of type
<literal>void (*callback) (gpointer instance, gint arg1, gpointer user_data)</literal> where the #gint parameter denotes an enumeration type..
</para>

@closure: the #GClosure to which the marshaller belongs
@return_value: ignored
@n_param_values: 2
@param_values: a #GValue array holding the instance and the enumeration parameter
@invocation_hint: the invocation hint given as the the last argument
  to g_closure_invoke()
@marshal_data: additional data specified when registering the marshaller


<!-- ##### FUNCTION g_cclosure_marshal_VOID__FLAGS ##### -->
<para>
A marshaller for a #GCClosure with a callback of type
<literal>void (*callback) (gpointer instance, gint arg1, gpointer user_data)</literal> where the #gint parameter denotes a flags type
denotes a flags type.
</para>

@closure: the #GClosure to which the marshaller belongs
@return_value: ignored
@n_param_values: 2
@param_values: a #GValue array holding the instance and the flags parameter
@invocation_hint: the invocation hint given as the the last argument
  to g_closure_invoke()
@marshal_data: additional data specified when registering the marshaller


<!-- ##### FUNCTION g_cclosure_marshal_VOID__FLOAT ##### -->
<para>
A marshaller for a #GCClosure with a callback of type
<literal>void (*callback) (gpointer instance, gfloat arg1, gpointer user_data)</literal>.
</para>

@closure: the #GClosure to which the marshaller belongs
@return_value: ignored
@n_param_values: 2
@param_values: a #GValue array holding the instance and the #gfloat parameter
@invocation_hint: the invocation hint given as the the last argument
  to g_closure_invoke()
@marshal_data: additional data specified when registering the marshaller


<!-- ##### FUNCTION g_cclosure_marshal_VOID__DOUBLE ##### -->
<para>
A marshaller for a #GCClosure with a callback of type
<literal>void (*callback) (gpointer instance, gdouble arg1, gpointer user_data)</literal>.
</para>

@closure: the #GClosure to which the marshaller belongs
@return_value: ignored
@n_param_values: 2
@param_values: a #GValue array holding the instance and the #gdouble parameter
@invocation_hint: the invocation hint given as the the last argument
  to g_closure_invoke()
@marshal_data: additional data specified when registering the marshaller


<!-- ##### FUNCTION g_cclosure_marshal_VOID__STRING ##### -->
<para>
A marshaller for a #GCClosure with a callback of type
<literal>void (*callback) (gpointer instance, const gchar *arg1, gpointer user_data)</literal>.
</para>

@closure: the #GClosure to which the marshaller belongs
@return_value: ignored
@n_param_values: 2
@param_values: a #GValue array holding the instance and the #gchar* parameter
@invocation_hint: the invocation hint given as the the last argument
  to g_closure_invoke()
@marshal_data: additional data specified when registering the marshaller


<!-- ##### FUNCTION g_cclosure_marshal_VOID__PARAM ##### -->
<para>
A marshaller for a #GCClosure with a callback of type
<literal>void (*callback) (gpointer instance, GParamSpec *arg1, gpointer user_data)</literal>.
</para>

@closure: the #GClosure to which the marshaller belongs
@return_value: ignored
@n_param_values: 2
@param_values: a #GValue array holding the instance and the #GParamSpec* parameter
@invocation_hint: the invocation hint given as the the last argument
  to g_closure_invoke()
@marshal_data: additional data specified when registering the marshaller


<!-- ##### FUNCTION g_cclosure_marshal_VOID__BOXED ##### -->
<para>
A marshaller for a #GCClosure with a callback of type
<literal>void (*callback) (gpointer instance, GBoxed *arg1, gpointer user_data)</literal>.
</para>

@closure: the #GClosure to which the marshaller belongs
@return_value: ignored
@n_param_values: 2
@param_values: a #GValue array holding the instance and the #GBoxed* parameter
@invocation_hint: the invocation hint given as the the last argument
  to g_closure_invoke()
@marshal_data: additional data specified when registering the marshaller


<!-- ##### FUNCTION g_cclosure_marshal_VOID__POINTER ##### -->
<para>
A marshaller for a #GCClosure with a callback of type
<literal>void (*callback) (gpointer instance, gpointer arg1, gpointer user_data)</literal>.
</para>

@closure: the #GClosure to which the marshaller belongs
@return_value: ignored
@n_param_values: 2
@param_values: a #GValue array holding the instance and the #gpointer parameter
@invocation_hint: the invocation hint given as the the last argument
  to g_closure_invoke()
@marshal_data: additional data specified when registering the marshaller


<!-- ##### FUNCTION g_cclosure_marshal_VOID__OBJECT ##### -->
<para>
A marshaller for a #GCClosure with a callback of type
<literal>void (*callback) (gpointer instance, GOBject *arg1, gpointer user_data)</literal>.
</para>

@closure: the #GClosure to which the marshaller belongs
@return_value: ignored
@n_param_values: 2
@param_values: a #GValue array holding the instance and the #GObject* parameter
@invocation_hint: the invocation hint given as the the last argument
  to g_closure_invoke()
@marshal_data: additional data specified when registering the marshaller


<!-- ##### FUNCTION g_cclosure_marshal_STRING__OBJECT_POINTER ##### -->
<para>
A marshaller for a #GCClosure with a callback of type
<literal>void (*callback) (gpointer instance, GObject *arg1, gpointer arg2, gpointer user_data)</literal>.
</para>

@closure: the #GClosure to which the marshaller belongs
@return_value: ignored
@n_param_values: 3
@param_values: a #GValue array holding instance, arg1 and arg2
@invocation_hint: the invocation hint given as the the last argument
  to g_closure_invoke()
@marshal_data: additional data specified when registering the marshaller


<!-- ##### FUNCTION g_cclosure_marshal_VOID__UINT_POINTER ##### -->
<para>
A marshaller for a #GCClosure with a callback of type
<literal>void (*callback) (gpointer instance, guint arg1, gpointer arg2, gpointer user_data)</literal>.
</para>

@closure: the #GClosure to which the marshaller belongs
@return_value: ignored
@n_param_values: 3
@param_values: a #GValue array holding instance, arg1 and arg2
@invocation_hint: the invocation hint given as the the last argument
  to g_closure_invoke()
@marshal_data: additional data specified when registering the marshaller


<!-- ##### FUNCTION g_cclosure_marshal_BOOLEAN__FLAGS ##### -->
<para>
A marshaller for a #GCClosure with a callback of type
<literal>gboolean (*callback) (gpointer instance, gint arg1, gpointer user_data)</literal> where the #gint parameter
denotes a flags type.
</para>

@closure: the #GClosure to which the marshaller belongs
@return_value: a #GValue which can store the returned #gboolean
@n_param_values: 2
@param_values: a #GValue array holding instance and arg1
@invocation_hint: the invocation hint given as the the last argument
  to g_closure_invoke()
@marshal_data: additional data specified when registering the marshaller


<!-- ##### MACRO g_cclosure_marshal_BOOL__FLAGS ##### -->
<para>
Another name for g_cclosure_marshal_BOOLEAN__FLAGS().
</para>