gobject/gobject.h

   1 /* GObject - GLib Type, Object, Parameter and Signal Library
   2  * Copyright (C) 1998-1999, 2000-2001 Tim Janik and Red Hat, Inc.
   3  *
   4  * This library is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU Lesser General Public
   6  * License as published by the Free Software Foundation; either
   7  * version 2 of the License, or (at your option) any later version.
   8  *
   9  * This library is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * Lesser General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU Lesser General
  15  * Public License along with this library; if not, write to the
  16  * Free Software Foundation, Inc., 59 Temple Place, Suite 330,
  17  * Boston, MA 02111-1307, USA.
  18  */
  19 #if !defined (__GLIB_GOBJECT_H_INSIDE__) && !defined (GOBJECT_COMPILATION)
  20 #error "Only <glib-object.h> can be included directly."
  21 #endif
  22
  23 #ifndef __G_OBJECT_H__
  24 #define __G_OBJECT_H__
  25
  26 #include        <gobject/gtype.h>
  27 #include        <gobject/gvalue.h>
  28 #include        <gobject/gparam.h>
  29 #include        <gobject/gclosure.h>
  30 #include        <gobject/gsignal.h>
  31
  32 G_BEGIN_DECLS
  33
  34 /* --- type macros --- */
  35 /**
  36  * G_TYPE_IS_OBJECT:
  37  * @type: Type id to check
  38  *
  39  * Check if the passed in type id is a %G_TYPE_OBJECT or derived from it.
  40  *
  41  * Returns: %FALSE or %TRUE, indicating whether @type is a %G_TYPE_OBJECT.
  42  */
  43 #define G_TYPE_IS_OBJECT(type)      (G_TYPE_FUNDAMENTAL (type) == G_TYPE_OBJECT)
  44 /**
  45  * G_OBJECT:
  46  * @object: Object which is subject to casting.
  47  *
  48  * Casts a #GObject or derived pointer into a (GObject*) pointer.
  49  * Depending on the current debugging level, this function may invoke
  50  * certain runtime checks to identify invalid casts.
  51  */
  52 #define G_OBJECT(object)            (G_TYPE_CHECK_INSTANCE_CAST ((object), G_TYPE_OBJECT, GObject))
  53 /**
  54  * G_OBJECT_CLASS:
  55  * @class: a valid #GObjectClass
  56  *
  57  * Casts a derived #GObjectClass structure into a #GObjectClass structure.
  58  */
  59 #define G_OBJECT_CLASS(class)       (G_TYPE_CHECK_CLASS_CAST ((class), G_TYPE_OBJECT, GObjectClass))
  60 /**
  61  * G_IS_OBJECT:
  62  * @object: Instance to check for being a %G_TYPE_OBJECT.
  63  *
  64  * Checks whether a valid #GTypeInstance pointer is of type %G_TYPE_OBJECT.
  65  */
  66 #define G_IS_OBJECT(object)         (G_TYPE_CHECK_INSTANCE_TYPE ((object), G_TYPE_OBJECT))
  67 /**
  68  * G_IS_OBJECT_CLASS:
  69  * @class: a #GObjectClass
  70  *
  71  * Checks whether @class "is a" valid #GObjectClass structure of type
  72  * %G_TYPE_OBJECT or derived.
  73  */
  74 #define G_IS_OBJECT_CLASS(class)    (G_TYPE_CHECK_CLASS_TYPE ((class), G_TYPE_OBJECT))
  75 /**
  76  * G_OBJECT_GET_CLASS:
  77  * @object: a #GObject instance.
  78  *
  79  * Get the class structure associated to a #GObject instance.
  80  *
  81  * Returns: pointer to object class structure.
  82  */
  83 #define G_OBJECT_GET_CLASS(object)  (G_TYPE_INSTANCE_GET_CLASS ((object), G_TYPE_OBJECT, GObjectClass))
  84 /**
  85  * G_OBJECT_TYPE:
  86  * @object: Object to return the type id for.
  87  *
  88  * Get the type id of an object.
  89  *
  90  * Returns: Type id of @object.
  91  */
  92 #define G_OBJECT_TYPE(object)       (G_TYPE_FROM_INSTANCE (object))
  93 /**
  94  * G_OBJECT_TYPE_NAME:
  95  * @object: Object to return the type name for.
  96  *
  97  * Get the name of an object's type.
  98  *
  99  * Returns: Type name of @object. The string is owned by the type system and
 100  *  should not be freed.
 101  */
 102 #define G_OBJECT_TYPE_NAME(object)  (g_type_name (G_OBJECT_TYPE (object)))
 103 /**
 104  * G_OBJECT_CLASS_TYPE:
 105  * @class: a valid #GObjectClass
 106  *
 107  * Get the type id of a class structure.
 108  *
 109  * Returns: Type id of @class.
 110  */
 111 #define G_OBJECT_CLASS_TYPE(class)  (G_TYPE_FROM_CLASS (class))
 112 /**
 113  * G_OBJECT_CLASS_NAME:
 114  * @class: a valid #GObjectClass
 115  *
 116  * Return the name of a class structure's type.
 117  *
 118  * Returns: Type name of @class. The string is owned by the type system and
 119  *  should not be freed.
 120  */
 121 #define G_OBJECT_CLASS_NAME(class)  (g_type_name (G_OBJECT_CLASS_TYPE (class)))
 122 /**
 123  * G_VALUE_HOLDS_OBJECT:
 124  * @value: a valid #GValue structure
 125  *
 126  * Checks whether the given #GValue can hold values derived from type %G_TYPE_OBJECT.
 127  *
 128  * Returns: %TRUE on success.
 129  */
 130 #define G_VALUE_HOLDS_OBJECT(value) (G_TYPE_CHECK_VALUE_TYPE ((value), G_TYPE_OBJECT))
 131
 132 /* --- type macros --- */
 133 /**
 134  * G_TYPE_INITIALLY_UNOWNED:
 135  *
 136  * The type for #GInitiallyUnowned.
 137  */
 138 #define G_TYPE_INITIALLY_UNOWNED              (g_initially_unowned_get_type())
 139 /**
 140  * G_INITIALLY_UNOWNED:
 141  * @object: Object which is subject to casting.
 142  *
 143  * Casts a #GInitiallyUnowned or derived pointer into a (GInitiallyUnowned*)
 144  * pointer. Depending on the current debugging level, this function may invoke
 145  * certain runtime checks to identify invalid casts.
 146  */
 147 #define G_INITIALLY_UNOWNED(object)           (G_TYPE_CHECK_INSTANCE_CAST ((object), G_TYPE_INITIALLY_UNOWNED, GInitiallyUnowned))
 148 /**
 149  * G_INITIALLY_UNOWNED_CLASS:
 150  * @class: a valid #GInitiallyUnownedClass
 151  *
 152  * Casts a derived #GInitiallyUnownedClass structure into a
 153  * #GInitiallyUnownedClass structure.
 154  */
 155 #define G_INITIALLY_UNOWNED_CLASS(class)      (G_TYPE_CHECK_CLASS_CAST ((class), G_TYPE_INITIALLY_UNOWNED, GInitiallyUnownedClass))
 156 /**
 157  * G_IS_INITIALLY_UNOWNED:
 158  * @object: Instance to check for being a %G_TYPE_INITIALLY_UNOWNED.
 159  *
 160  * Checks whether a valid #GTypeInstance pointer is of type %G_TYPE_INITIALLY_UNOWNED.
 161  */
 162 #define G_IS_INITIALLY_UNOWNED(object)        (G_TYPE_CHECK_INSTANCE_TYPE ((object), G_TYPE_INITIALLY_UNOWNED))
 163 /**
 164  * G_IS_INITIALLY_UNOWNED_CLASS:
 165  * @class: a #GInitiallyUnownedClass
 166  *
 167  * Checks whether @class "is a" valid #GInitiallyUnownedClass structure of type
 168  * %G_TYPE_INITIALLY_UNOWNED or derived.
 169  */
 170 #define G_IS_INITIALLY_UNOWNED_CLASS(class)   (G_TYPE_CHECK_CLASS_TYPE ((class), G_TYPE_INITIALLY_UNOWNED))
 171 /**
 172  * G_INITIALLY_UNOWNED_GET_CLASS:
 173  * @object: a #GInitiallyUnowned instance.
 174  *
 175  * Get the class structure associated to a #GInitiallyUnowned instance.
 176  *
 177  * Returns: pointer to object class structure.
 178  */
 179 #define G_INITIALLY_UNOWNED_GET_CLASS(object) (G_TYPE_INSTANCE_GET_CLASS ((object), G_TYPE_INITIALLY_UNOWNED, GInitiallyUnownedClass))
 180 /* GInitiallyUnowned ia a GObject with initially floating reference count */
 181
 182
 183 /* --- typedefs & structures --- */
 184 typedef struct _GObject                  GObject;
 185 typedef struct _GObjectClass             GObjectClass;
 186 typedef struct _GObject                  GInitiallyUnowned;
 187 typedef struct _GObjectClass             GInitiallyUnownedClass;
 188 typedef struct _GObjectConstructParam    GObjectConstructParam;
 189 /**
 190  * GObjectGetPropertyFunc:
 191  * @object: a #GObject
 192  * @property_id: the numeric id under which the property was registered with
 193  *  g_object_class_install_property().
 194  * @value: a #GValue to return the property value in
 195  * @pspec: the #GParamSpec describing the property
 196  *
 197  * The type of the @get_property function of #GObjectClass.
 198  */
 199 typedef void (*GObjectGetPropertyFunc)  (GObject      *object,
 200                                          guint         property_id,
 201                                          GValue       *value,
 202                                          GParamSpec   *pspec);
 203 /**
 204  * GObjectSetPropertyFunc:
 205  * @object: a #GObject
 206  * @property_id: the numeric id under which the property was registered with
 207  *  g_object_class_install_property().
 208  * @value: the new value for the property
 209  * @pspec: the #GParamSpec describing the property
 210  *
 211  * The type of the @set_property function of #GObjectClass.
 212  */
 213 typedef void (*GObjectSetPropertyFunc)  (GObject      *object,
 214                                          guint         property_id,
 215                                          const GValue *value,
 216                                          GParamSpec   *pspec);
 217 /**
 218  * GObjectFinalizeFunc:
 219  * @object: the #GObject being finalized
 220  *
 221  * The type of the @finalize function of #GObjectClass.
 222  */
 223 typedef void (*GObjectFinalizeFunc)     (GObject      *object);
 224 /**
 225  * GWeakNotify:
 226  * @data: data that was provided when the weak reference was established
 227  * @where_the_object_was: the object being finalized
 228  *
 229  * A #GWeakNotify function can be added to an object as a callback that gets
 230  * triggered when the object is finalized. Since the object is already being
 231  * finalized when the #GWeakNotify is called, there's not much you could do
 232  * with the object, apart from e.g. using its address as hash-index or the like.
 233  */
 234 typedef void (*GWeakNotify)             (gpointer      data,
 235                                          GObject      *where_the_object_was);
 236 /**
 237  * GObject:
 238  *
 239  * All the fields in the <structname>GObject</structname> structure are private
 240  * to the #GObject implementation and should never be accessed directly.
 241  */
 242 struct  _GObject
 243 {
 244   GTypeInstance  g_type_instance;
 245
 246   /*< private >*/
 247   volatile guint ref_count;
 248   GData         *qdata;
 249 };
 250 /**
 251  * GObjectClass:
 252  * @g_type_class: the parent class
 253  * @constructor: the @constructor function is called by g_object_new () to
 254  *  complete the object initialization after all the construction properties are
 255  *  set. The first thing a @constructor implementation must do is chain up to the
 256  *  @constructor of the parent class. Overriding @constructor should be rarely
 257  *  needed, e.g. to handle construct properties, or to implement singletons.
 258  * @set_property: the generic setter for all properties of this type. Should be
 259  *  overridden for every type with properties. Implementations of @set_property
 260  *  don't need to emit property change notification explicitly, this is handled
 261  *  by the type system.
 262  * @get_property: the generic getter for all properties of this type. Should be
 263  *  overridden for every type with properties.
 264  * @dispose: the @dispose function is supposed to drop all references to other
 265  *  objects, but keep the instance otherwise intact, so that client method
 266  *  invocations still work. It may be run multiple times (due to reference
 267  *  loops). Before returning, @dispose should chain up to the @dispose method
 268  *  of the parent class.
 269  * @finalize: instance finalization function, should finish the finalization of
 270  *  the instance begun in @dispose and chain up to the @finalize method of the
 271  *  parent class.
 272  * @dispatch_properties_changed: emits property change notification for a bunch
 273  *  of properties. Overriding @dispatch_properties_changed should be rarely
 274  *  needed.
 275  * @notify: the class closure for the notify signal
 276  * @constructed: the @constructed function is called by g_object_new() as the
 277  *  final step of the object creation process.  At the point of the call, all
 278  *  construction properties have been set on the object.  The purpose of this
 279  *  call is to allow for object initialisation steps that can only be performed
 280  *  after construction properties have been set.  @constructed implementors
 281  *  should chain up to the @constructed call of their parent class to allow it
 282  *  to complete its initialisation.
 283  *
 284  * The class structure for the <structname>GObject</structname> type.
 285  *
 286  * <example>
 287  * <title>Implementing singletons using a constructor</title>
 288  * <programlisting>
 289  * static MySingleton *the_singleton = NULL;
 290  *
 291  * static GObject*
 292  * my_singleton_constructor (GType                  type,
 293  *                           guint                  n_construct_params,
 294  *                           GObjectConstructParam *construct_params)
 295  * {
 296  *   GObject *object;
 297  *
 298  *   if (!the_singleton)
 299  *     {
 300  *       object = G_OBJECT_CLASS (parent_class)->constructor (type,
 301  *                                                            n_construct_params,
 302  *                                                            construct_params);
 303  *       the_singleton = MY_SINGLETON (object);
 304  *     }
 305  *   else
 306  *     object = g_object_ref (G_OBJECT (the_singleton));
 307  *
 308  *   return object;
 309  * }
 310  * </programlisting></example>
 311  */
 312 struct  _GObjectClass
 313 {
 314   GTypeClass   g_type_class;
 315
 316   /*< private >*/
 317   GSList      *construct_properties;
 318
 319   /*< public >*/
 320   /* seldom overidden */
 321   GObject*   (*constructor)     (GType                  type,
 322                                  guint                  n_construct_properties,
 323                                  GObjectConstructParam *construct_properties);
 324   /* overridable methods */
 325   void       (*set_property)            (GObject        *object,
 326                                          guint           property_id,
 327                                          const GValue   *value,
 328                                          GParamSpec     *pspec);
 329   void       (*get_property)            (GObject        *object,
 330                                          guint           property_id,
 331                                          GValue         *value,
 332                                          GParamSpec     *pspec);
 333   void       (*dispose)                 (GObject        *object);
 334   void       (*finalize)                (GObject        *object);
 335   /* seldom overidden */
 336   void       (*dispatch_properties_changed) (GObject      *object,
 337                                              guint         n_pspecs,
 338                                              GParamSpec  **pspecs);
 339   /* signals */
 340   void       (*notify)                  (GObject        *object,
 341                                          GParamSpec     *pspec);
 342
 343   /* called when done constructing */
 344   void       (*constructed)             (GObject        *object);
 345
 346   /*< private >*/
 347   gsize         flags;
 348
 349   /* padding */
 350   gpointer      pdummy[6];
 351 };
 352 /**
 353  * GObjectConstructParam:
 354  * @pspec: the #GParamSpec of the construct parameter
 355  * @value: the value to set the parameter to
 356  *
 357  * The <structname>GObjectConstructParam</structname> struct is an auxiliary
 358  * structure used to hand #GParamSpec/#GValue pairs to the @constructor of
 359  * a #GObjectClass.
 360  */
 361 struct _GObjectConstructParam
 362 {
 363   GParamSpec *pspec;
 364   GValue     *value;
 365 };
 366
 367 /**
 368  * GInitiallyUnowned:
 369  *
 370  * All the fields in the <structname>GInitiallyUnowned</structname> structure
 371  * are private to the #GInitiallyUnowned implementation and should never be
 372  * accessed directly.
 373  */
 374 /**
 375  * GInitiallyUnownedClass:
 376  *
 377  * The class structure for the <structname>GInitiallyUnowned</structname> type.
 378  */
 379
 380
 381 /* --- prototypes --- */
 382 GType       g_initially_unowned_get_type      (void);
 383 void        g_object_class_install_property   (GObjectClass   *oclass,
 384                                                guint           property_id,
 385                                                GParamSpec     *pspec);
 386 GParamSpec* g_object_class_find_property      (GObjectClass   *oclass,
 387                                                const gchar    *property_name);
 388 GParamSpec**g_object_class_list_properties    (GObjectClass   *oclass,
 389                                                guint          *n_properties);
 390 void        g_object_class_override_property  (GObjectClass   *oclass,
 391                                                guint           property_id,
 392                                                const gchar    *name);
 393 void        g_object_class_install_properties (GObjectClass   *oclass,
 394                                                guint           n_pspecs,
 395                                                GParamSpec    **pspecs);
 396
 397 void        g_object_interface_install_property (gpointer     g_iface,
 398                                                  GParamSpec  *pspec);
 399 GParamSpec* g_object_interface_find_property    (gpointer     g_iface,
 400                                                  const gchar *property_name);
 401 GParamSpec**g_object_interface_list_properties  (gpointer     g_iface,
 402                                                  guint       *n_properties_p);
 403
 404 GType       g_object_get_type                 (void) G_GNUC_CONST;
 405 gpointer    g_object_new                      (GType           object_type,
 406                                                const gchar    *first_property_name,
 407                                                ...);
 408 gpointer    g_object_newv                     (GType           object_type,
 409                                                guint           n_parameters,
 410                                                GParameter     *parameters);
 411 GObject*    g_object_new_valist               (GType           object_type,
 412                                                const gchar    *first_property_name,
 413                                                va_list         var_args);
 414 void        g_object_set                      (gpointer        object,
 415                                                const gchar    *first_property_name,
 416                                                ...) G_GNUC_NULL_TERMINATED;
 417 void        g_object_get                      (gpointer        object,
 418                                                const gchar    *first_property_name,
 419                                                ...) G_GNUC_NULL_TERMINATED;
 420 gpointer    g_object_connect                  (gpointer        object,
 421                                                const gchar    *signal_spec,
 422                                                ...) G_GNUC_NULL_TERMINATED;
 423 void        g_object_disconnect               (gpointer        object,
 424                                                const gchar    *signal_spec,
 425                                                ...) G_GNUC_NULL_TERMINATED;
 426 void        g_object_set_valist               (GObject        *object,
 427                                                const gchar    *first_property_name,
 428                                                va_list         var_args);
 429 void        g_object_get_valist               (GObject        *object,
 430                                                const gchar    *first_property_name,
 431                                                va_list         var_args);
 432 void        g_object_set_property             (GObject        *object,
 433                                                const gchar    *property_name,
 434                                                const GValue   *value);
 435 void        g_object_get_property             (GObject        *object,
 436                                                const gchar    *property_name,
 437                                                GValue         *value);
 438 void        g_object_freeze_notify            (GObject        *object);
 439 void        g_object_notify                   (GObject        *object,
 440                                                const gchar    *property_name);
 441 void        g_object_notify_by_pspec          (GObject        *object,
 442                                                GParamSpec     *pspec);
 443 void        g_object_thaw_notify              (GObject        *object);
 444 gboolean    g_object_is_floating              (gpointer        object);
 445 gpointer    g_object_ref_sink                 (gpointer        object);
 446 gpointer    g_object_ref                      (gpointer        object);
 447 void        g_object_unref                    (gpointer        object);
 448 void        g_object_weak_ref                 (GObject        *object,
 449                                                GWeakNotify     notify,
 450                                                gpointer        data);
 451 void        g_object_weak_unref               (GObject        *object,
 452                                                GWeakNotify     notify,
 453                                                gpointer        data);
 454 void        g_object_add_weak_pointer         (GObject        *object,
 455                                                gpointer       *weak_pointer_location);
 456 void        g_object_remove_weak_pointer      (GObject        *object,
 457                                                gpointer       *weak_pointer_location);
 458
 459 /**
 460  * GToggleNotify:
 461  * @data: Callback data passed to g_object_add_toggle_ref()
 462  * @object: The object on which g_object_add_toggle_ref() was called.
 463  * @is_last_ref: %TRUE if the toggle reference is now the
 464  *  last reference to the object. %FALSE if the toggle
 465  *  reference was the last reference and there are now other
 466  *  references.
 467  *
 468  * A callback function used for notification when the state
 469  * of a toggle reference changes. See g_object_add_toggle_ref().
 470  */
 471 typedef void (*GToggleNotify) (gpointer      data,
 472                                GObject      *object,
 473                                gboolean      is_last_ref);
 474
 475 void g_object_add_toggle_ref    (GObject       *object,
 476                                  GToggleNotify  notify,
 477                                  gpointer       data);
 478 void g_object_remove_toggle_ref (GObject       *object,
 479                                  GToggleNotify  notify,
 480                                  gpointer       data);
 481
 482 gpointer    g_object_get_qdata                (GObject        *object,
 483                                                GQuark          quark);
 484 void        g_object_set_qdata                (GObject        *object,
 485                                                GQuark          quark,
 486                                                gpointer        data);
 487 void        g_object_set_qdata_full           (GObject        *object,
 488                                                GQuark          quark,
 489                                                gpointer        data,
 490                                                GDestroyNotify  destroy);
 491 gpointer    g_object_steal_qdata              (GObject        *object,
 492                                                GQuark          quark);
 493 gpointer    g_object_get_data                 (GObject        *object,
 494                                                const gchar    *key);
 495 void        g_object_set_data                 (GObject        *object,
 496                                                const gchar    *key,
 497                                                gpointer        data);
 498 void        g_object_set_data_full            (GObject        *object,
 499                                                const gchar    *key,
 500                                                gpointer        data,
 501                                                GDestroyNotify  destroy);
 502 gpointer    g_object_steal_data               (GObject        *object,
 503                                                const gchar    *key);
 504 void        g_object_watch_closure            (GObject        *object,
 505                                                GClosure       *closure);
 506 GClosure*   g_cclosure_new_object             (GCallback       callback_func,
 507                                                GObject        *object);
 508 GClosure*   g_cclosure_new_object_swap        (GCallback       callback_func,
 509                                                GObject        *object);
 510 GClosure*   g_closure_new_object              (guint           sizeof_closure,
 511                                                GObject        *object);
 512 void        g_value_set_object                (GValue         *value,
 513                                                gpointer        v_object);
 514 gpointer    g_value_get_object                (const GValue   *value);
 515 gpointer    g_value_dup_object                (const GValue   *value);
 516 gulong      g_signal_connect_object           (gpointer        instance,
 517                                                const gchar    *detailed_signal,
 518                                                GCallback       c_handler,
 519                                                gpointer        gobject,
 520                                                GConnectFlags   connect_flags);
 521
 522 /*< protected >*/
 523 void        g_object_force_floating           (GObject        *object);
 524 void        g_object_run_dispose              (GObject        *object);
 525
 526
 527 void        g_value_take_object               (GValue         *value,
 528                                                gpointer        v_object);
 529 #ifndef G_DISABLE_DEPRECATED
 530 void        g_value_set_object_take_ownership (GValue         *value,
 531                                                gpointer        v_object);
 532 #endif
 533
 534 #if !defined(G_DISABLE_DEPRECATED) || defined(GTK_COMPILATION)
 535 gsize       g_object_compat_control           (gsize           what,
 536                                                gpointer        data);
 537 #endif
 538
 539 /* --- implementation macros --- */
 540 #define G_OBJECT_WARN_INVALID_PSPEC(object, pname, property_id, pspec) \
 541 G_STMT_START { \
 542   GObject *_object = (GObject*) (object); \
 543   GParamSpec *_pspec = (GParamSpec*) (pspec); \
 544   guint _property_id = (property_id); \
 545   g_warning ("%s: invalid %s id %u for \"%s\" of type `%s' in `%s'", \
 546              G_STRLOC, \
 547              (pname), \
 548              _property_id, \
 549              _pspec->name, \
 550              g_type_name (G_PARAM_SPEC_TYPE (_pspec)), \
 551              G_OBJECT_TYPE_NAME (_object)); \
 552 } G_STMT_END
 553 /**
 554  * G_OBJECT_WARN_INVALID_PROPERTY_ID:
 555  * @object: the #GObject on which set_property() or get_property() was called
 556  * @property_id: the numeric id of the property
 557  * @pspec: the #GParamSpec of the property
 558  *
 559  * This macro should be used to emit a standard warning about unexpected
 560  * properties in set_property() and get_property() implementations.
 561  */
 562 #define G_OBJECT_WARN_INVALID_PROPERTY_ID(object, property_id, pspec) \
 563     G_OBJECT_WARN_INVALID_PSPEC ((object), "property", (property_id), (pspec))
 564
 565 void    g_clear_object (volatile GObject **object_ptr);
 566 #define g_clear_object(object_ptr) \
 567   G_STMT_START {                                                             \
 568     /* Only one access, please */                                            \
 569     gpointer *_p = (gpointer) (object_ptr);                                  \
 570     gpointer _o;                                                             \
 571                                                                              \
 572     do                                                                       \
 573       _o = g_atomic_pointer_get (_p);                                        \
 574     while G_UNLIKELY (!g_atomic_pointer_compare_and_exchange (_p, _o, NULL));\
 575                                                                              \
 576     if (_o)                                                                  \
 577       g_object_unref (_o);                                                   \
 578   } G_STMT_END
 579
 580 G_END_DECLS
 581
 582 #endif /* __G_OBJECT_H__ */