GtkObject The base class of the GTK+ type hierarchy. #GtkObject is the base class for all widgets, and for a few non-widget objects such as #GtkAdjustment. #GtkObject predates #GObject; non-widgets that derive from #GtkObject rather than #GObject do so for backward compatibility reasons. The most interesting difference between #GtkObject and #GObject is the "floating" reference count. A #GObject is created with a reference count of 1, owned by the creator of the #GObject. (The owner of a reference is the code section that has the right to call g_object_unref() in order to remove that reference.) A #GtkObject is created with a reference count of 1 also, but it isn't owned by anyone; calling g_object_unref() on the newly-created #GtkObject is incorrect. Instead, the initial reference count of a #GtkObject is "floating". The floating reference can be removed by anyone at any time, by calling gtk_object_sink(). gtk_object_sink() does nothing if an object is already sunk (has no floating reference). When you add a widget to its parent container, the parent container will do this: g_object_ref (G_OBJECT (child_widget)); gtk_object_sink (GTK_OBJECT (child_widget)); This means that the container now owns a reference to the child widget (since it called g_object_ref()), and the child widget has no floating reference. The purpose of the floating reference is to keep the child widget alive until you add it to a parent container: button = gtk_button_new (); /* button has one floating reference to keep it alive */ gtk_container_add (GTK_CONTAINER (container), button); /* button has one non-floating reference owned by the container */ #GtkWindow is a special case, because GTK+ itself will ref/sink it on creation. That is, after calling gtk_window_new(), the #GtkWindow will have one reference which is owned by GTK+, and no floating references. One more factor comes into play: the "destroy" signal, emitted by the gtk_object_destroy() method. The "destroy" signal asks all code owning a reference to an object to release said reference. So, for example, if you call gtk_object_destroy() on a #GtkWindow, GTK+ will release the reference count that it owns; if you call gtk_object_destroy() on a #GtkButton, then the button will be removed from its parent container and the parent container will release its reference to the button. Because these references are released, calling gtk_object_destroy() should result in freeing all memory associated with an object, unless some buggy code fails to release its references in response to the "destroy" signal. Freeing memory (referred to as finalization only happens if the reference count reaches zero. Some simple rules for handling #GtkObject: Never call g_object_unref() unless you have previously called g_object_ref(), even if you created the #GtkObject. (Note: this is not true for #GObject; for #GObject, the creator of the object owns a reference.) Call gtk_object_destroy() to get rid of most objects in most cases. In particular, widgets are almost always destroyed in this way. Because of the floating reference count, you don't need to worry about reference counting for widgets and toplevel windows, unless you explicitly call g_object_ref() yourself. #GObject The object itself. You should never use these members directly - use the accessing macros instead. Gets the type of an object. @object: a #GtkObject. Gets the name of an objects type. @object: a #GtkObject. Tells about the state of the object. @GTK_IN_DESTRUCTION: @GTK_FLOATING: whether the object is orphaned. Objects that take strong hold of an object may gtk_object_sink() it, after obtaining there own references, if they believe they are nearly primary ownership of the object. GTK_CONNECTED: refers to whether are signals are connected to this object. @GTK_RESERVED_1: reserved for future use @GTK_RESERVED_2: reserved for future use Gets the #GtkObjectFlags for an object without directly accessing its members. @obj: the object whose flags are returned. Evaluates to %TRUE if the object still has its floating reference count. See the overview documentation for #GtkObject. @obj: the object to examine. Tests whether a #GtkObject has had a signal connected to it. @obj: the object to examine. Turns on certain object flags. (Private) @obj: the object to affect. @flag: the flags to set. Turns off certain object flags. (Private) @obj: the object to affect. @flag: the flags to unset. Possible flags indicating how an argument should be treated. Deprecated in favor of #GParamSpec features. @GTK_ARG_READABLE: the argument is readable. (i.e. can be queried) @GTK_ARG_WRITABLE: the argument is writable. (i.e. settable) @GTK_ARG_CONSTRUCT: the argument needs construction. @GTK_ARG_CONSTRUCT_ONLY: the argument needs construction (and will be set once during object creation), but is otherwise cannot be set. Hence this flag is not allowed with #GTK_ARG_WRITABLE, and is redundant with #GTK_ARG_CONSTRUCT. @GTK_ARG_CHILD_ARG: an argument type that applies to (and may be different for) each child. Used by #GtkContainer. Constructs an object given its arguments, enumerated in the call to the function. Deprecated in favor of g_object_new(). @type: the type identifying this object. Returned by gtk_type_unique() (although for a properly-written object it should be accessible through a #GTK_TYPE_FOO macro.) @first_property_name: name of the first property to set when constructing the object. @Varargs: the first argument's value, followed by any number of name/argument-value pairs, terminated with %NULL. @Returns: the new #GtkObject. Removes the floating reference from a #GtkObject, if it exists; otherwise does nothing. See the #GtkObject overview documentation at the top of the page. @object: the object to sink. Increases the reference count of the object. Deprecated in favor of g_object_ref(). @object: the object to reference. @Returns: @object. Decreases the reference count of an object. When its reference count drops to 0, the object is finalized (i.e. its memory is freed). Deprecated in favor of g_object_unref(). @object: the object to dereference. Adds a weak reference callback to an object. Deprecated in favor of g_object_weak_ref(). Weak references are used for notification when an object is finalized. They are called "weak references" because they allow you to safely hold a pointer to an object without calling g_object_ref() (g_object_ref() adds a strong reference, that is, forces the object to stay alive). @object: object to weakly reference. @notify: callback to invoke before the object is freed. @data: extra data to pass to #notify. Removes a weak reference callback to an object. @object: object stop weakly referencing. @notify: callback to search for. @data: data to search for. Emits the "destroy" signal notifying all reference holders that they should release the #GtkObject. See the overview documentation at the top of the page for more details. The memory for the object itself won't be deleted until its reference count actually drops to 0; gtk_object_destroy() merely asks reference holders to release their references, it does not free the object. @object: the object to destroy. Gets properties of an object. Deprecated in favor of g_object_get(). @object: a #GtkObject. @first_property_name: name of first property to get the value for. @Varargs: %NULL-terminated list of name-return location pairs. Sets properties on an object. Deprecated in favor of g_object_set(). void set_box_properties (GtkBox* box) { gtk_object_set (GTK_OBJECT (box), "homogeneous", TRUE, "spacing", 8, NULL); } @object: a #GtkObject. @first_property_name: name of the first property to set @Varargs: the value of the first argument, followed optionally by more name/value pairs, followed by %NULL. Deprecated in favor of g_object_set_data(). Each object carries around a table of associations from strings to pointers. This function lets you set an association. If the object already had an association with that name, the old association will be destroyed. @object: object containing the associations. @key: name of the key. @data: data to associate with that key. Deprecated in favor of g_object_set_data_full(). Like gtk_object_set_data() except it adds notification for when the association is destroyed, either by gtk_object_remove_data() or when the object is destroyed. @object: object containing the associations. @key: name of the key. @data: data to associate with that key. @destroy: function to call when the association is destroyed. Deprecated in favor of setting object data to %NULL using g_object_set_data(). Removes a specified datum from the object's data associations (the object_data). Subsequent calls to gtk_object_get_data() will return %NULL. If you specified a destroy handler with gtk_object_set_data_full(), it will be invoked. @object: the object maintaining the association. @key: name of the key for that association. Deprecated in favor of g_object_get_data(). Get a named field from the object's table of associations (the object_data). @object: the object maintaining the associations. @key: name of the key for that association. @Returns: the data if found, or %NULL if no such data exists. Deprecated in favor of g_object_steal_data(). Remove a specified datum from the object's data associations (the object_data), without invoking the association's destroy handler. Just like gtk_object_remove_data() except that any destroy handler will be ignored. Therefore this only affects data set using gtk_object_set_data_full(). @object: the object maintaining the association. @key: name of the key for that association. Deprecated in favor of g_object_set_data(). For convenience, every object offers a generic user data pointer. This function sets it. This function is equivalent to gtk_object_set_data (object, "user_data", data). @object: the object whose user data should be set. @data: the new value for the user data. Deprecated in favor of g_object_get_data(). Get the object's user data pointer. This is intended to be a pointer for your convenience in writing applications. @object: the object. @Returns: the user data field for object. Deprecated in favor of the #GObject property system including #GParamSpec. Add a new type of argument to an object class. Usually this is called when registering a new type of object. @arg_name: fully qualify object name, for example GtkObject::user_data. @arg_type: type of the argument. @arg_flags: bitwise-OR of the #GtkArgFlags enum. (Whether the argument is settable or gettable, whether it is set when the object is constructed.) @arg_id: an internal number, passed in from here to the "set_arg" and "get_arg" handlers of the object. Deprecated in favor of g_object_set_qdata(). Just like gtk_object_set_data() except that it takes a #GQuark instead of a string, so it is slightly faster. Use gtk_object_data_try_key() and gtk_object_data_force_id() to get an id from a string. @object: object containing the associations. @data_id: quark of the key. @data: data to associate with that key. Deprecated in favor of g_object_set_qdata_full(). Just like gtk_object_set_data_full() except that it takes a #GQuark instead of a string, so it is slightly faster. Use gtk_object_data_try_key() and gtk_object_data_force_id() to get an id from a string. @object: object containing the associations. @data_id: quark of the key. @data: data to associate with that key. @destroy: function to call when the association is destroyed. Deprecated in favor of g_object_get_qdata(). Just like gtk_object_get_data() except that it takes a #GQuark instead of a string, so it is slightly faster. Use gtk_object_data_try_key() and gtk_object_data_force_id() to get an id from a string. @object: object containing the associations. @data_id: quark of the key. @Returns: the data if found, or %NULL if no such data exists. Deprecated in favor of g_object_set_qdata() called with data of %NULL. Just like gtk_object_remove_data() except that it takes a #GQuark instead of a string, so it is slightly faster. Remove a specified datum from the object's data associations. Subsequent calls to gtk_object_get_data() will return %NULL. Use gtk_object_data_try_key() and gtk_object_data_force_id() to get an id from a string. @object: object containing the associations. @data_id: quark of the key. Deprecated in favor of g_object_steal_qdata(). Just like gtk_object_remove_no_notify() except that it takes a #GQuark instead of a string, so it is slightly faster. Use gtk_object_data_try_key() and gtk_object_data_force_id() to get an id from a string. @object: object containing the associations. @key_id: quark of the key. @data_id: Useless deprecated macro. Ignore it. Useless deprecated macro. Ignore it. Signals that all holders of a reference to the #GtkObject should release the reference that they hold. May result in finalization of the object if all references are released. @object: the object which received the signal. A pointer for convenience when programming applications. Deprecated.