1 <!-- ##### SECTION Title ##### -->
4 <!-- ##### SECTION Short_Description ##### -->
5 The base class of the GTK+ type hierarchy.
7 <!-- ##### SECTION Long_Description ##### -->
9 <title>Description</title>
11 #GtkObject is the base class for all widgets, and for a few
12 non-widget objects such as #GtkAdjustment. #GtkObject predates
13 #GObject; non-widgets that derive from #GtkObject rather than
14 #GObject do so for backward compatibility reasons.
17 The most interesting difference between #GtkObject and #GObject is the
18 "floating" reference count. A #GObject is created with a reference count of 1,
19 owned by the creator of the #GObject. (The owner of a reference is the code
20 section that has the right to call g_object_unref() in order to remove that
21 reference.) A #GtkObject is created with a reference count of 1 also, but it
22 isn't owned by anyone; calling g_object_unref() on the newly-created #GtkObject
23 is incorrect. Instead, the initial reference count of a #GtkObject is "floating".
24 The floating reference can be removed by anyone at any time, by calling
25 gtk_object_sink(). gtk_object_sink() does nothing if an object is already
26 sunk (has no floating reference).
29 When you add a widget to its parent container, the parent container
31 <informalexample><programlisting>
32 g_object_ref (G_OBJECT (child_widget));
33 gtk_object_sink (GTK_OBJECT (child_widget));
34 </programlisting></informalexample>
35 This means that the container now owns a reference to the child widget (since
36 it called g_object_ref()), and the child widget has no floating reference.
39 The purpose of the floating reference is to keep the child widget alive
40 until you add it to a parent container:
41 <informalexample><programlisting>
42 button = gtk_button_new (<!-- -->);
43 /* button has one floating reference to keep it alive */
44 gtk_container_add (GTK_CONTAINER (container), button);
45 /* button has one non-floating reference owned by the container */
46 </programlisting></informalexample>
49 #GtkWindow is a special case, because GTK+ itself will ref/sink it on creation.
50 That is, after calling gtk_window_new(), the #GtkWindow will have one
51 reference which is owned by GTK+, and no floating references.
55 One more factor comes into play: the "destroy" signal, emitted by the
56 gtk_object_destroy() method. The "destroy" signal asks all code owning a
57 reference to an object to release said reference. So, for example, if you call
58 gtk_object_destroy() on a #GtkWindow, GTK+ will release the reference count that
59 it owns; if you call gtk_object_destroy() on a #GtkButton, then the button will
60 be removed from its parent container and the parent container will release its
61 reference to the button. Because these references are released, calling
62 gtk_object_destroy() should result in freeing all memory associated with an
63 object, unless some buggy code fails to release its references in response to
64 the "destroy" signal. Freeing memory (referred to as
65 <firstterm>finalization</firstterm> only happens if the reference count reaches
70 Some simple rules for handling #GtkObject:
73 Never call g_object_unref() unless you have previously called g_object_ref(),
74 even if you created the #GtkObject. (Note: this is <emphasis>not</emphasis>
75 true for #GObject; for #GObject, the creator of the object owns a reference.)
78 Call gtk_object_destroy() to get rid of most objects in most cases.
79 In particular, widgets are almost always destroyed in this way.
81 <listitem><para> Because of the floating reference count, you don't need to
82 worry about reference counting for widgets and toplevel windows, unless you
83 explicitly call g_object_ref() yourself.</para></listitem>
89 <!-- ##### SECTION See_Also ##### -->
94 <!-- ##### STRUCT GtkObject ##### -->
96 The object itself. You should never use these members directly -
97 use the accessing macros instead.
101 <!-- ##### MACRO GTK_OBJECT_TYPE ##### -->
103 Gets the type of an object.
106 @object: a #GtkObject.
109 <!-- ##### MACRO GTK_OBJECT_TYPE_NAME ##### -->
111 Gets the name of an objects type.
114 @object: a #GtkObject.
117 <!-- ##### ENUM GtkObjectFlags ##### -->
119 Tells about the state of the object.
122 @GTK_IN_DESTRUCTION: the object is currently being destroyed. This is used
123 internally by GTK+ to prevent reinvokations during destruction.
124 @GTK_FLOATING: the object is orphaned. Objects that take strong hold of an
125 object may gtk_object_sink() it, after obtaining their own references, if
126 they believe they are nearly primary ownership of the object.
127 GTK_CONNECTED: signals are connected to this object.
128 @GTK_RESERVED_1: reserved for future use
129 @GTK_RESERVED_2: reserved for future use
131 <!-- ##### MACRO GTK_OBJECT_FLAGS ##### -->
133 Gets the #GtkObjectFlags for an object without directly
134 accessing its members.
137 @obj: the object whose flags are returned.
140 <!-- ##### MACRO GTK_OBJECT_FLOATING ##### -->
142 Evaluates to %TRUE if the object still has its floating reference count.
143 See the overview documentation for #GtkObject.
146 @obj: the object to examine.
149 <!-- ##### ENUM GtkArgFlags ##### -->
151 Possible flags indicating how an argument should be treated.
152 Deprecated in favor of #GParamSpec features.
155 @GTK_ARG_READABLE: the argument is readable. (i.e. can be queried)
156 @GTK_ARG_WRITABLE: the argument is writable. (i.e. settable)
157 @GTK_ARG_CONSTRUCT: the argument needs construction.
158 @GTK_ARG_CONSTRUCT_ONLY: the argument needs construction (and will
159 be set once during object creation), but is otherwise cannot be
160 set. Hence this flag is not allowed with #GTK_ARG_WRITABLE,
161 and is redundant with #GTK_ARG_CONSTRUCT.
162 @GTK_ARG_CHILD_ARG: an argument type that applies to (and may be different for)
163 each child. Used by #GtkContainer.
165 <!-- ##### FUNCTION gtk_object_new ##### -->
167 Constructs an object given its arguments, enumerated in the call to the
168 function. Deprecated in favor of g_object_new().
171 @type: the type identifying this object. Returned by gtk_type_unique()
172 (although for a properly-written object it should be accessible through
173 a #GTK_TYPE_FOO macro.)
174 @first_property_name: name of the first property to set when constructing
176 @Varargs: the first argument's value, followed by any number of
177 name/argument-value pairs, terminated with %NULL.
178 @Returns: the new #GtkObject.
181 <!-- ##### FUNCTION gtk_object_sink ##### -->
183 Removes the floating reference from a #GtkObject, if it exists;
184 otherwise does nothing. See the #GtkObject overview documentation at
188 @object: the object to sink.
191 <!-- ##### FUNCTION gtk_object_ref ##### -->
193 Increases the reference count of the object.
194 Deprecated in favor of g_object_ref().
197 @object: the object to reference.
201 <!-- ##### FUNCTION gtk_object_unref ##### -->
203 Decreases the reference count of an object. When its reference count drops
204 to 0, the object is finalized (i.e. its memory is freed). Deprecated in
205 favor of g_object_unref().
208 @object: the object to dereference.
211 <!-- ##### FUNCTION gtk_object_weakref ##### -->
213 Adds a weak reference callback to an object. Deprecated in favor of
214 g_object_weak_ref(). Weak references are used for notification when an object is
215 finalized. They are called "weak references" because they allow you to safely
216 hold a pointer to an object without calling g_object_ref() (g_object_ref() adds
217 a strong reference, that is, forces the object to stay alive).
220 @object: object to weakly reference.
221 @notify: callback to invoke before the object is freed.
222 @data: extra data to pass to #notify.
225 <!-- ##### FUNCTION gtk_object_weakunref ##### -->
227 Removes a weak reference callback to an object.
230 @object: object stop weakly referencing.
231 @notify: callback to search for.
232 @data: data to search for.
235 <!-- ##### FUNCTION gtk_object_destroy ##### -->
237 Emits the "destroy" signal notifying all reference holders that they should
238 release the #GtkObject. See the overview documentation at the top of the
239 page for more details.
242 The memory for the object itself won't be deleted until
243 its reference count actually drops to 0; gtk_object_destroy() merely asks
244 reference holders to release their references, it does not free the object.
247 @object: the object to destroy.
250 <!-- ##### FUNCTION gtk_object_get ##### -->
252 Gets properties of an object. Deprecated in favor of g_object_get().
255 @object: a #GtkObject.
256 @first_property_name: name of first property to get the value for.
257 @Varargs: %NULL-terminated list of name-return location pairs.
260 <!-- ##### FUNCTION gtk_object_set ##### -->
262 Sets properties on an object. Deprecated in favor of g_object_set().
267 void set_box_properties (GtkBox* box)
269 gtk_object_set (GTK_OBJECT (box), "homogeneous", TRUE,
277 @object: a #GtkObject.
278 @first_property_name: name of the first property to set
279 @Varargs: the value of the first argument, followed optionally
280 by more name/value pairs, followed by %NULL.
283 <!-- ##### FUNCTION gtk_object_set_data ##### -->
285 Deprecated in favor of g_object_set_data().
286 Each object carries around a table of associations from
287 strings to pointers. This function lets you set an association.
290 If the object already had an association with that name,
291 the old association will be destroyed.
294 @object: object containing the associations.
295 @key: name of the key.
296 @data: data to associate with that key.
299 <!-- ##### FUNCTION gtk_object_set_data_full ##### -->
301 Deprecated in favor of g_object_set_data_full().
302 Like gtk_object_set_data() except it adds notification
303 for when the association is destroyed, either by
304 gtk_object_remove_data() or when the object is destroyed.
307 @object: object containing the associations.
308 @key: name of the key.
309 @data: data to associate with that key.
310 @destroy: function to call when the association is destroyed.
313 <!-- ##### FUNCTION gtk_object_remove_data ##### -->
315 Deprecated in favor of setting object data to %NULL using g_object_set_data().
316 Removes a specified datum from the object's data associations (the object_data).
317 Subsequent calls to gtk_object_get_data() will return %NULL.
320 If you specified a destroy handler with gtk_object_set_data_full(),
324 @object: the object maintaining the association.
325 @key: name of the key for that association.
328 <!-- ##### FUNCTION gtk_object_get_data ##### -->
330 Deprecated in favor of g_object_get_data().
331 Get a named field from the object's table of associations (the object_data).
334 @object: the object maintaining the associations.
335 @key: name of the key for that association.
336 @Returns: the data if found, or %NULL if no such data exists.
339 <!-- ##### FUNCTION gtk_object_remove_no_notify ##### -->
341 Deprecated in favor of g_object_steal_data().
342 Remove a specified datum from the object's data associations (the object_data),
343 without invoking the association's destroy handler.
346 Just like gtk_object_remove_data() except that any destroy handler
348 Therefore this only affects data set using gtk_object_set_data_full().
351 @object: the object maintaining the association.
352 @key: name of the key for that association.
355 <!-- ##### FUNCTION gtk_object_set_user_data ##### -->
357 Deprecated in favor of g_object_set_data().
358 For convenience, every object offers a generic user data
359 pointer. This function sets it.
362 This function is equivalent to
363 <literal>gtk_object_set_data (object, "user_data", data)</literal>.
366 @object: the object whose user data should be set.
367 @data: the new value for the user data.
370 <!-- ##### FUNCTION gtk_object_get_user_data ##### -->
372 Deprecated in favor of g_object_get_data().
373 Get the object's user data pointer.
376 This is intended to be a pointer for your convenience in
377 writing applications.
381 @Returns: the user data field for object.
384 <!-- ##### FUNCTION gtk_object_add_arg_type ##### -->
386 Deprecated in favor of the #GObject property system including #GParamSpec.
387 Add a new type of argument to an object class.
388 Usually this is called when registering a new type of object.
391 @arg_name: fully qualify object name, for example GtkObject::user_data.
392 @arg_type: type of the argument.
393 @arg_flags: bitwise-OR of the #GtkArgFlags enum. (Whether the argument is
394 settable or gettable, whether it is set when the object is constructed.)
395 @arg_id: an internal number, passed in from here to the "set_arg" and
396 "get_arg" handlers of the object.
399 <!-- ##### FUNCTION gtk_object_set_data_by_id ##### -->
401 Deprecated in favor of g_object_set_qdata().
402 Just like gtk_object_set_data() except that it takes
403 a #GQuark instead of a string, so it is slightly faster.
406 Use gtk_object_data_try_key() and gtk_object_data_force_id()
407 to get an id from a string.
410 @object: object containing the associations.
411 @data_id: quark of the key.
412 @data: data to associate with that key.
415 <!-- ##### FUNCTION gtk_object_set_data_by_id_full ##### -->
417 Deprecated in favor of g_object_set_qdata_full().
418 Just like gtk_object_set_data_full() except that it takes
419 a #GQuark instead of a string, so it is slightly faster.
422 Use gtk_object_data_try_key() and gtk_object_data_force_id()
423 to get an id from a string.
426 @object: object containing the associations.
427 @data_id: quark of the key.
428 @data: data to associate with that key.
429 @destroy: function to call when the association is destroyed.
432 <!-- ##### FUNCTION gtk_object_get_data_by_id ##### -->
434 Deprecated in favor of g_object_get_qdata().
435 Just like gtk_object_get_data() except that it takes
436 a #GQuark instead of a string, so it is slightly faster.
439 Use gtk_object_data_try_key() and gtk_object_data_force_id()
440 to get an id from a string.
443 @object: object containing the associations.
444 @data_id: quark of the key.
445 @Returns: the data if found, or %NULL if no such data exists.
448 <!-- ##### FUNCTION gtk_object_remove_data_by_id ##### -->
450 Deprecated in favor of g_object_set_qdata() called with data of %NULL.
451 Just like gtk_object_remove_data() except that it takes
452 a #GQuark instead of a string, so it is slightly faster.
455 Remove a specified datum from the object's data associations.
456 Subsequent calls to gtk_object_get_data() will return %NULL.
459 Use gtk_object_data_try_key() and gtk_object_data_force_id()
460 to get an id from a string.
463 @object: object containing the associations.
464 @data_id: quark of the key.
467 <!-- ##### FUNCTION gtk_object_remove_no_notify_by_id ##### -->
469 Deprecated in favor of g_object_steal_qdata().
470 Just like gtk_object_remove_no_notify() except that it takes
471 a #GQuark instead of a string, so it is slightly faster.
474 Use gtk_object_data_try_key() and gtk_object_data_force_id()
475 to get an id from a string.
478 @object: object containing the associations.
479 @key_id: quark of the key.
480 <!-- # Unused Parameters # -->
484 <!-- ##### MACRO gtk_object_data_try_key ##### -->
486 Useless deprecated macro. Ignore it.
491 <!-- ##### MACRO gtk_object_data_force_id ##### -->
493 Useless deprecated macro. Ignore it.
498 <!-- ##### SIGNAL GtkObject::destroy ##### -->
500 Signals that all holders of a reference to the #GtkObject should release
501 the reference that they hold. May result in finalization of the object
502 if all references are released.
505 @object: the object which received the signal.
507 <!-- ##### ARG GtkObject:user-data ##### -->