<!-- ##### SECTION Title ##### --> Closures <!-- ##### SECTION Short_Description ##### --> Functions as first-class objects <!-- ##### SECTION Long_Description ##### --> <para> A #GClosure represents a callback supplied by the programmer. It will generally comprise a function of some kind and a marshaller used to call it. It is the reponsibility of the marshaller to convert the arguments for the invocation from #GValue<!-- -->s into a suitable form, perform the callback on the converted arguments, and transform the return value back into a #GValue. </para> <para> In the case of C programs, a closure usually just holds a pointer to a function and maybe a data argument, and the marshaller converts between #GValue<!-- --> and native C types. The GObject library provides the #GCClosure type for this purpose. Bindings for other languages need marshallers which convert between #GValue<!-- -->s and suitable representations in the runtime of the language in order to use functions written in that languages as callbacks. </para> <para> Within GObject, closures play an important role in the implementation of signals. When a signal is registered, the @c_marshaller argument to g_signal_new() specifies the default C marshaller for any closure which is connected to this signal. GObject provides a number of C marshallers for this purpose, see the g_cclosure_marshal_*() functions. Additional C marshallers can be generated with the <link linkend="glib-genmarshal" >glib-genmarshal</link> utility. Closures can be explicitly connected to signals with g_signal_connect_closure(), but it usually more convenient to let GObject create a closure automatically by using one of the g_signal_connect_*() functions which take a callback function/user data pair. </para> <para> Using closures has a number of important advantages over a simple callback function/data pointer combination: <itemizedlist> <listitem><para> Closures allow the callee to get the types of the callback parameters, which means that language bindings don't have to write individual glue for each callback type. </para></listitem> <listitem><para> The reference counting of #GClosure makes it easy to handle reentrancy right; if a callback is removed while it is being invoked, the closure and it's parameters won't be freed until the invocation finishes. </para></listitem> <listitem><para> g_closure_invalidate() and invalidation notifiers allow callbacks to be automatically removed when the objects they point to go away. </para></listitem> </itemizedlist> </para> <!-- ##### SECTION See_Also ##### --> <para> </para> <!-- ##### SECTION Stability_Level ##### --> <!-- ##### MACRO G_CLOSURE_NEEDS_MARSHAL ##### --> <para> Returns %TRUE if a #GClosureMarshal marshaller has not yet been set on @closure. See g_closure_set_marshal(). </para> @closure: a #GClosure <!-- ##### MACRO G_CLOSURE_N_NOTIFIERS ##### --> <para> Returns the total number of notifiers connected with the closure @cl. The count includes the meta marshaller, the finalize and invalidate notifiers and the marshal guards. Note that each guard counts as two notifiers. See g_closure_set_meta_marshal(), g_closure_add_finalize_notifier(), g_closure_add_invalidate_notifier() and g_closure_add_marshal_guards(). </para> @cl: a #GClosure <!-- ##### MACRO G_CCLOSURE_SWAP_DATA ##### --> <para> Returns whether the user data of the #GCClosure should be passed as the first parameter to the callback. See g_cclosure_new_swap(). </para> @cclosure: a #GCClosure <!-- ##### MACRO G_CALLBACK ##### --> <para> Cast a function pointer to a #GCallback. </para> @f: a function pointer. <!-- ##### USER_FUNCTION GCallback ##### --> <para> The type used for callback functions in structure definitions and function signatures. This doesn't mean that all callback functions must take no parameters and return void. The required signature of a callback function is determined by the context in which is used (e.g. the signal to which it is connected). Use G_CALLBACK() to cast the callback function to a #GCallback. </para> <!-- ##### STRUCT GClosure ##### --> <para> A #GClosure represents a callback supplied by the programmer. </para> @in_marshal: Indicates whether the closure is currently being invoked with g_closure_invoke() @is_invalid: Indicates whether the closure has been invalidated by g_closure_invalidate() <!-- ##### MACRO G_TYPE_CLOSURE ##### --> <para> The #GType for #GClosure. </para> <!-- ##### STRUCT GCClosure ##### --> <para> A #GCClosure is a specialization of #GClosure for C function callbacks. </para> @closure: the #GClosure @callback: the callback function <!-- ##### USER_FUNCTION GClosureMarshal ##### --> <para> The type used for marshaller functions. </para> @closure: the #GClosure to which the marshaller belongs @return_value: a #GValue to store the return value. May be %NULL if the callback of @closure doesn't return a value. @n_param_values: the length of the @param_values array @param_values: an array of #GValue<!-- -->s holding the arguments on which to invoke the callback of @closure @invocation_hint: the invocation hint given as the the last argument to g_closure_invoke() @marshal_data: additional data specified when registering the marshaller, see g_closure_set_marshal() and g_closure_set_meta_marshal() <!-- ##### USER_FUNCTION GClosureNotify ##### --> <para> The type used for the various notification callbacks which can be registered on closures. </para> @data: data specified when registering the notification callback @closure: the #GClosure on which the notification is emitted <!-- ##### FUNCTION g_cclosure_new ##### --> <para> Creates a new closure which invokes @callback_func with @user_data as the last parameter. </para> @callback_func: the function to invoke @user_data: user data to pass to @callback_func @destroy_data: destroy notify to be called when @user_data is no longer used @Returns: a new #GCClosure <!-- ##### FUNCTION g_cclosure_new_swap ##### --> <para> Creates a new closure which invokes @callback_func with @user_data as the first parameter. </para> @callback_func: the function to invoke @user_data: user data to pass to @callback_func @destroy_data: destroy notify to be called when @user_data is no longer used @Returns: a new #GCClosure <!-- ##### FUNCTION g_cclosure_new_object ##### --> <para> A variant of g_cclosure_new() which uses @object as @user_data and calls g_object_watch_closure() on @object and the created closure. This function is useful when you have a callback closely associated with a #GObject, and want the callback to no longer run after the object is is freed. </para> @callback_func: the function to invoke @object: a #GObject pointer to pass to @callback_func @Returns: a new #GCClosure <!-- ##### FUNCTION g_cclosure_new_object_swap ##### --> <para> A variant of g_cclosure_new_swap() which uses @object as @user_data and calls g_object_watch_closure() on @object and the created closure. This function is useful when you have a callback closely associated with a #GObject, and want the callback to no longer run after the object is is freed. </para> @callback_func: the function to invoke @object: a #GObject pointer to pass to @callback_func @Returns: a new #GCClosure <!-- ##### FUNCTION g_closure_new_object ##### --> <para> A variant of g_closure_new_simple() which stores @object in the @data field of the closure and calls g_object_watch_closure() on @object and the created closure. This function is mainly useful when implementing new types of closures. </para> @sizeof_closure: the size of the structure to allocate, must be at least <literal>sizeof (GClosure)</literal> @object: a #GObject pointer to store in the @data field of the newly allocated #GClosure @Returns: a newly allocated #GClosure <!-- ##### FUNCTION g_closure_ref ##### --> <para> Increments the reference count on a closure to force it staying alive while the caller holds a pointer to it. </para> @closure: #GClosure to increment the reference count on @Returns: The @closure passed in, for convenience <!-- ##### FUNCTION g_closure_sink ##### --> <para> Takes over the initial ownership of a closure. Each closure is initially created in a<firstterm>floating</firstterm> state, which means that the initial reference count is not owned by any caller. g_closure_sink() checks to see if the object is still floating, and if so, unsets the floating state and decreases the reference count. If the closure is not floating, g_closure_sink() does nothing. The reason for the existance of the floating state is to prevent cumbersome code sequences like: <programlisting> closure = g_cclosure_new (cb_func, cb_data); g_source_set_closure (source, closure); g_closure_unref (closure); /* XXX GObject doesn't really need this */ </programlisting> Because g_source_set_closure() (and similar functions) take ownership of the initial reference count, if it is unowned, we instead can write: <programlisting> g_source_set_closure (source, g_cclosure_new (cb_func, cb_data)); </programlisting> </para> <para> Generally, this function is used together with g_closure_ref(). Ane example of storing a closure for later notification looks like: <informalexample><programlisting> static GClosure *notify_closure = NULL; void foo_notify_set_closure (GClosure *closure) { if (notify_closure) g_closure_unref (notify_closure); notify_closure = closure; if (notify_closure) { g_closure_ref (notify_closure); g_closure_sink (notify_closure); } } </programlisting></informalexample> </para> <para> Because g_closure_sink() may decrement the reference count of a closure (if it hasn't been called on @closure yet) just like g_closure_unref(), g_closure_ref() should be called prior to this function. </para> @closure: #GClosure to decrement the initial reference count on, if it's still being held <!-- ##### FUNCTION g_closure_unref ##### --> <para> Decrements the reference count of a closure after it was previously incremented by the same caller. If no other callers are using the closure, then the closure will be destroyed and freed. </para> @closure: #GClosure to decrement the reference count on <!-- ##### FUNCTION g_closure_invoke ##### --> <para> Invokes the closure, i.e. executes the callback represented by the @closure. </para> @closure: a #GClosure @return_value: a #GValue to store the return value. May be %NULL if the callback of @closure doesn't return a value. @n_param_values: the length of the @param_values array @param_values: an array of #GValue<!-- -->s holding the arguments on which to invoke the callback of @closure @invocation_hint: a context-dependent invocation hint <!-- ##### FUNCTION g_closure_invalidate ##### --> <para> Sets a flag on the closure to indicate that it's calling environment has become invalid, and thus causes any future invocations of g_closure_invoke() on this @closure to be ignored. Also, invalidation notifiers installed on the closure will be called at this point. Note that unless you are holding a reference to the closure yourself, the invalidation notifiers may unref the closure and cause it to be destroyed, so if you need to access the closure after calling g_closure_invalidate(), make sure that you've previously called g_closure_ref(). </para> <para> Note that g_closure_invalidate() will also be called when the reference count of a closure drops to zero (unless it has already been invalidated before). </para> @closure: GClosure to invalidate <!-- ##### FUNCTION g_closure_add_finalize_notifier ##### --> <para> Registers a finalization notifier which will be called when the reference count of @closure goes down to 0. Multiple finalization notifiers on a single closure are invoked in unspecified order. If a single call to g_closure_unref() results in the closure being both invalidated and finalized, then the invalidate notifiers will be run before the finalize notifiers. </para> @closure: a #GClosure @notify_data: data to pass to @notify_func @notify_func: the callback function to register <!-- ##### FUNCTION g_closure_add_invalidate_notifier ##### --> <para> Registers an invalidation notifier which will be called when the @closure is invalidated with g_closure_invalidate(). Invalidation notifiers are invoked before finalization notifiers, in an unspecified order. </para> @closure: a #GClosure @notify_data: data to pass to @notify_func @notify_func: the callback function to register <!-- ##### FUNCTION g_closure_remove_finalize_notifier ##### --> <para> Removes a finalization notifier. Notifiers are automatically removed after they are run. </para> @closure: a #GClosure @notify_data: data which was passed to g_closure_add_finalize_notifier() when registering @notify_func @notify_func: the callback function to remove <!-- ##### FUNCTION g_closure_remove_invalidate_notifier ##### --> <para> Removes a invalidation notifier. Notifiers are automatically removed after they are run. </para> @closure: a #GClosure @notify_data: data which was passed to g_closure_add_invalidate_notifier() when registering @notify_func @notify_func: the callback function to remove <!-- ##### FUNCTION g_closure_new_simple ##### --> <para> Allocates a struct of the given size and initializes the initial part as a #GClosure. This function is mainly useful when implementing new types of closures. </para> <informalexample> <programlisting> typedef struct _MyClosure MyClosure; struct _MyClosure { GClosure closure; /* extra data goes here */ }; static void my_closure_finalize (gpointer notify_data, GClosure *closure) { MyClosure *my_closure = (MyClosure *)closure; /* free extra data here */ } 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 @marshal_data 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 use some different technique to retrieve the callbakc 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>