struct GObject

struct GObject;

All the fields in the GObject structure are private to the GObject implementation and should never be accessed directly.

struct GObjectClass

struct GObjectClass {
  GTypeClass   g_type_class;

  /* seldom overidden */
  GObject*   (*constructor)     (GType                  type,
                                 guint                  n_construct_properties,
                                 GObjectConstructParam *construct_properties);
  /* overridable methods */
  void       (*set_property)		(GObject        *object,
                                         guint           property_id,
                                         const GValue   *value,
                                         GParamSpec     *pspec);
  void       (*get_property)		(GObject        *object,
                                         guint           property_id,
                                         GValue         *value,
                                         GParamSpec     *pspec);
  void       (*dispose)			(GObject        *object);
  void       (*finalize)		(GObject        *object);
  /* seldom overidden */
  void       (*dispatch_properties_changed) (GObject      *object,
					     guint	   n_pspecs,
					     GParamSpec  **pspecs);
  /* signals */
  void	     (*notify)			(GObject *object,
					 GParamSpec *pspec);

  /* called when done constructing */
  void	     (*constructed)		(GObject *object);
};

The class structure for the GObject type.

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static MySingleton *the_singleton = NULL;

static GObject*
my_singleton_constructor (GType                  type,
                          guint                  n_construct_params,
                          GObjectConstructParam *construct_params)
{
  GObject *object;

  if (!the_singleton)
    {
      object = G_OBJECT_CLASS (parent_class)->constructor (type,
                                                           n_construct_params,
                                                           construct_params);
      the_singleton = MY_SINGLETON (object);
    }
  else
    object = g_object_ref (G_OBJECT (the_singleton));

  return object;
}

struct GObjectConstructParam

struct GObjectConstructParam {
  GParamSpec *pspec;
  GValue     *value;
};

The GObjectConstructParam struct is an auxiliary structure used to hand GParamSpec/GValue pairs to the constructor of a GObjectClass.

GObjectGetPropertyFunc ()

void                (*GObjectGetPropertyFunc)           (GObject *object,
                                                         guint property_id,
                                                         GValue *value,
                                                         GParamSpec *pspec);

The type of the get_property function of GObjectClass.

GObjectSetPropertyFunc ()

void                (*GObjectSetPropertyFunc)           (GObject *object,
                                                         guint property_id,
                                                         const GValue *value,
                                                         GParamSpec *pspec);

The type of the set_property function of GObjectClass.

GObjectFinalizeFunc ()

void                (*GObjectFinalizeFunc)              (GObject *object);

The type of the finalize function of GObjectClass.

G_TYPE_IS_OBJECT()

#define G_TYPE_IS_OBJECT(type)      (G_TYPE_FUNDAMENTAL (type) == G_TYPE_OBJECT)

Check if the passed in type id is a G_TYPE_OBJECT or derived from it.

G_OBJECT()

#define G_OBJECT(object)            (G_TYPE_CHECK_INSTANCE_CAST ((object), G_TYPE_OBJECT, GObject))

Casts a GObject or derived pointer into a (GObject*) pointer. Depending on the current debugging level, this function may invoke certain runtime checks to identify invalid casts.

G_IS_OBJECT()

#define G_IS_OBJECT(object)         (G_TYPE_CHECK_INSTANCE_TYPE ((object), G_TYPE_OBJECT))

Checks whether a valid GTypeInstance pointer is of type G_TYPE_OBJECT.

G_OBJECT_CLASS()

#define G_OBJECT_CLASS(class)       (G_TYPE_CHECK_CLASS_CAST ((class), G_TYPE_OBJECT, GObjectClass))

Casts a derived GObjectClass structure into a GObjectClass structure.

G_IS_OBJECT_CLASS()

#define G_IS_OBJECT_CLASS(class)    (G_TYPE_CHECK_CLASS_TYPE ((class), G_TYPE_OBJECT))

Checks whether class "is a" valid GObjectClass structure of type G_TYPE_OBJECT or derived.

G_OBJECT_GET_CLASS()

#define G_OBJECT_GET_CLASS(object)  (G_TYPE_INSTANCE_GET_CLASS ((object), G_TYPE_OBJECT, GObjectClass))

Get the class structure associated to a GObject instance.

G_OBJECT_TYPE()

#define G_OBJECT_TYPE(object)       (G_TYPE_FROM_INSTANCE (object))

Get the type id of an object.

G_OBJECT_TYPE_NAME()

#define G_OBJECT_TYPE_NAME(object)  (g_type_name (G_OBJECT_TYPE (object)))

Get the name of an object's type.

G_OBJECT_CLASS_TYPE()

#define G_OBJECT_CLASS_TYPE(class)  (G_TYPE_FROM_CLASS (class))

Get the type id of a class structure.

G_OBJECT_CLASS_NAME()

#define G_OBJECT_CLASS_NAME(class)  (g_type_name (G_OBJECT_CLASS_TYPE (class)))

Return the name of a class structure's type.

g_object_class_install_property ()

void                g_object_class_install_property     (GObjectClass *oclass,
                                                         guint property_id,
                                                         GParamSpec *pspec);

Installs a new property. This is usually done in the class initializer.

Note that it is possible to redefine a property in a derived class, by installing a property with the same name. This can be useful at times, e.g. to change the range of allowed values or the default value.

g_object_class_install_properties ()

void                g_object_class_install_properties   (GObjectClass *oclass,
                                                         guint n_pspecs,
                                                         GParamSpec **pspecs);

Installs new properties from an array of GParamSpecs. This is usually done in the class initializer.

The property id of each property is the index of each GParamSpec in the pspecs array.

The property id of 0 is treated specially by GObject and it should not be used to store a GParamSpec.

This function should be used if you plan to use a static array of GParamSpecs and g_object_notify_by_pspec(). For instance, this class initialization:

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enum {
  PROP_0, PROP_FOO, PROP_BAR, N_PROPERTIES
};

static GParamSpec *obj_properties[N_PROPERTIES] = { NULL, };

static void
my_object_class_init (MyObjectClass *klass)
{
  GObjectClass *gobject_class = G_OBJECT_CLASS (klass);

  obj_properties[PROP_FOO] =
    g_param_spec_int ("foo", "Foo", "Foo",
                      -1, G_MAXINT,
                      0,
                      G_PARAM_READWRITE);

  obj_properties[PROP_BAR] =
    g_param_spec_string ("bar", "Bar", "Bar",
                         NULL,
                         G_PARAM_READWRITE);

  gobject_class->set_property = my_object_set_property;
  gobject_class->get_property = my_object_get_property;
  g_object_class_install_properties (gobject_class,
                                     N_PROPERTIES,
                                     obj_properties);
}

allows calling g_object_notify_by_pspec() to notify of property changes:

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void
my_object_set_foo (MyObject *self, gint foo)
{
  if (self->foo != foo)
    {
      self->foo = foo;
      g_object_notify_by_pspec (G_OBJECT (self), obj_properties[PROP_FOO]);
    }
 }

Since 2.26

g_object_class_find_property ()

GParamSpec *        g_object_class_find_property        (GObjectClass *oclass,
                                                         const gchar *property_name);

Looks up the GParamSpec for a property of a class.

g_object_class_list_properties ()

GParamSpec **       g_object_class_list_properties      (GObjectClass *oclass,
                                                         guint *n_properties);

Get an array of GParamSpec* for all properties of a class.

g_object_class_override_property ()

void                g_object_class_override_property    (GObjectClass *oclass,
                                                         guint property_id,
                                                         const gchar *name);

Registers property_id as referring to a property with the name name in a parent class or in an interface implemented by oclass. This allows this class to override a property implementation in a parent class or to provide the implementation of a property from an interface.

Since 2.4

g_object_interface_install_property ()

void                g_object_interface_install_property (gpointer g_iface,
                                                         GParamSpec *pspec);

Add a property to an interface; this is only useful for interfaces that are added to GObject-derived types. Adding a property to an interface forces all objects classes with that interface to have a compatible property. The compatible property could be a newly created GParamSpec, but normally g_object_class_override_property() will be used so that the object class only needs to provide an implementation and inherits the property description, default value, bounds, and so forth from the interface property.

This function is meant to be called from the interface's default vtable initialization function (the class_init member of GTypeInfo.) It must not be called after after class_init has been called for any object types implementing this interface.

Since 2.4

g_object_interface_find_property ()

GParamSpec *        g_object_interface_find_property    (gpointer g_iface,
                                                         const gchar *property_name);

Find the GParamSpec with the given name for an interface. Generally, the interface vtable passed in as g_iface will be the default vtable from g_type_default_interface_ref(), or, if you know the interface has already been loaded, g_type_default_interface_peek().

Since 2.4

g_object_interface_list_properties ()

GParamSpec **       g_object_interface_list_properties  (gpointer g_iface,
                                                         guint *n_properties_p);

Lists the properties of an interface.Generally, the interface vtable passed in as g_iface will be the default vtable from g_type_default_interface_ref(), or, if you know the interface has already been loaded, g_type_default_interface_peek().

Since 2.4

g_object_new ()

gpointer            g_object_new                        (GType object_type,
                                                         const gchar *first_property_name,
                                                         ...);

Creates a new instance of a GObject subtype and sets its properties.

Construction parameters (see G_PARAM_CONSTRUCT, G_PARAM_CONSTRUCT_ONLY) which are not explicitly specified are set to their default values.

g_object_newv ()

gpointer            g_object_newv                       (GType object_type,
                                                         guint n_parameters,
                                                         GParameter *parameters);

Creates a new instance of a GObject subtype and sets its properties.

Construction parameters (see G_PARAM_CONSTRUCT, G_PARAM_CONSTRUCT_ONLY) which are not explicitly specified are set to their default values.

Rename to: g_object_new

struct GParameter

struct GParameter {
  const gchar *name;
  GValue       value;
};

The GParameter struct is an auxiliary structure used to hand parameter name/value pairs to g_object_newv().

g_object_ref ()

gpointer            g_object_ref                        (gpointer object);

Increases the reference count of object.

g_object_unref ()

void                g_object_unref                      (gpointer object);

Decreases the reference count of object. When its reference count drops to 0, the object is finalized (i.e. its memory is freed).

g_object_ref_sink ()

gpointer            g_object_ref_sink                   (gpointer object);

Increase the reference count of object, and possibly remove the floating reference, if object has a floating reference.

In other words, if the object is floating, then this call "assumes ownership" of the floating reference, converting it to a normal reference by clearing the floating flag while leaving the reference count unchanged. If the object is not floating, then this call adds a new normal reference increasing the reference count by one.

Since 2.10

g_clear_object ()

void                g_clear_object                      (volatile GObject **object_ptr);

Clears a reference to a GObject.

object_ptr must not be NULL.

If the reference is NULL then this function does nothing. Otherwise, the reference count of the object is decreased and the pointer is set to NULL.

This function is threadsafe and modifies the pointer atomically, using memory barriers where needed.

A macro is also included that allows this function to be used without pointer casts.

Since 2.28

GInitiallyUnowned

typedef struct _GObject                  GInitiallyUnowned;

All the fields in the GInitiallyUnowned structure are private to the GInitiallyUnowned implementation and should never be accessed directly.

GInitiallyUnownedClass

typedef struct _GObjectClass             GInitiallyUnownedClass;

The class structure for the GInitiallyUnowned type.

G_TYPE_INITIALLY_UNOWNED

#define G_TYPE_INITIALLY_UNOWNED	      (g_initially_unowned_get_type())

The type for GInitiallyUnowned.

g_object_is_floating ()

gboolean            g_object_is_floating                (gpointer object);

Checks whether object has a floating reference.

Since 2.10

g_object_force_floating ()

void                g_object_force_floating             (GObject *object);

This function is intended for GObject implementations to re-enforce a floating object reference. Doing this is seldom required: all GInitiallyUnowneds are created with a floating reference which usually just needs to be sunken by calling g_object_ref_sink().

Since 2.10

GWeakNotify ()

void                (*GWeakNotify)                      (gpointer data,
                                                         GObject *where_the_object_was);

A GWeakNotify function can be added to an object as a callback that gets triggered when the object is finalized. Since the object is already being finalized when the GWeakNotify is called, there's not much you could do with the object, apart from e.g. using its address as hash-index or the like.

g_object_weak_ref ()

void                g_object_weak_ref                   (GObject *object,
                                                         GWeakNotify notify,
                                                         gpointer data);

Adds a weak reference callback to an object. 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).

Note that the weak references created by this method are not thread-safe: they cannot safely be used in one thread if the object's last g_object_unref() might happen in another thread. Use GWeakRef if thread-safety is required.

g_object_weak_unref ()

void                g_object_weak_unref                 (GObject *object,
                                                         GWeakNotify notify,
                                                         gpointer data);

Removes a weak reference callback to an object.

g_object_add_weak_pointer ()

void                g_object_add_weak_pointer           (GObject *object,
                                                         gpointer *weak_pointer_location);

Adds a weak reference from weak_pointer to object to indicate that the pointer located at weak_pointer_location is only valid during the lifetime of object. When the object is finalized, weak_pointer will be set to NULL.

Note that as with g_object_weak_ref(), the weak references created by this method are not thread-safe: they cannot safely be used in one thread if the object's last g_object_unref() might happen in another thread. Use GWeakRef if thread-safety is required.

g_object_remove_weak_pointer ()

void                g_object_remove_weak_pointer        (GObject *object,
                                                         gpointer *weak_pointer_location);

Removes a weak reference from object that was previously added using g_object_add_weak_pointer(). The weak_pointer_location has to match the one used with g_object_add_weak_pointer().

GToggleNotify ()

void                (*GToggleNotify)                    (gpointer data,
                                                         GObject *object,
                                                         gboolean is_last_ref);

A callback function used for notification when the state of a toggle reference changes. See g_object_add_toggle_ref().

g_object_add_toggle_ref ()

void                g_object_add_toggle_ref             (GObject *object,
                                                         GToggleNotify notify,
                                                         gpointer data);

Increases the reference count of the object by one and sets a callback to be called when all other references to the object are dropped, or when this is already the last reference to the object and another reference is established.

This functionality is intended for binding object to a proxy object managed by another memory manager. This is done with two paired references: the strong reference added by g_object_add_toggle_ref() and a reverse reference to the proxy object which is either a strong reference or weak reference.

The setup is that when there are no other references to object, only a weak reference is held in the reverse direction from object to the proxy object, but when there are other references held to object, a strong reference is held. The notify callback is called when the reference from object to the proxy object should be toggled from strong to weak (is_last_ref true) or weak to strong (is_last_ref false).

Since a (normal) reference must be held to the object before calling g_object_add_toggle_ref(), the initial state of the reverse link is always strong.

Multiple toggle references may be added to the same gobject, however if there are multiple toggle references to an object, none of them will ever be notified until all but one are removed. For this reason, you should only ever use a toggle reference if there is important state in the proxy object.

Since 2.8

g_object_remove_toggle_ref ()

void                g_object_remove_toggle_ref          (GObject *object,
                                                         GToggleNotify notify,
                                                         gpointer data);

Removes a reference added with g_object_add_toggle_ref(). The reference count of the object is decreased by one.

Since 2.8

g_object_connect ()

gpointer            g_object_connect                    (gpointer object,
                                                         const gchar *signal_spec,
                                                         ...);

A convenience function to connect multiple signals at once.

The signal specs expected by this function have the form "modifier::signal_name", where modifier can be one of the following:

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menu->toplevel = g_object_connect (g_object_new (GTK_TYPE_WINDOW,
                                                   "type", GTK_WINDOW_POPUP,
                                                   "child", menu,
                                                   NULL),
                                     "signal::event", gtk_menu_window_event, menu,
                                     "signal::size_request", gtk_menu_window_size_request, menu,
                                     "signal::destroy", gtk_widget_destroyed, &menu->toplevel,
                                     NULL);

g_object_disconnect ()

void                g_object_disconnect                 (gpointer object,
                                                         const gchar *signal_spec,
                                                         ...);

A convenience function to disconnect multiple signals at once.

The signal specs expected by this function have the form "any_signal", which means to disconnect any signal with matching callback and data, or "any_signal::signal_name", which only disconnects the signal named "signal_name".

g_object_set ()

void                g_object_set                        (gpointer object,
                                                         const gchar *first_property_name,
                                                         ...);

Sets properties on an object.

g_object_get ()

void                g_object_get                        (gpointer object,
                                                         const gchar *first_property_name,
                                                         ...);

Gets properties of an object.

In general, a copy is made of the property contents and the caller is responsible for freeing the memory in the appropriate manner for the type, for instance by calling g_free() or g_object_unref().

 gint intval;
 gchar *strval;
 GObject *objval;

 g_object_get (my_object,
               "int-property", &intval,
               "str-property", &strval,
               "obj-property", &objval,
               NULL);

 // Do something with intval, strval, objval

 g_free (strval);
 g_object_unref (objval);

g_object_notify ()

void                g_object_notify                     (GObject *object,
                                                         const gchar *property_name);

Emits a "notify" signal for the property property_name on object.

When possible, eg. when signaling a property change from within the class that registered the property, you should use g_object_notify_by_pspec() instead.

g_object_notify_by_pspec ()

void                g_object_notify_by_pspec            (GObject *object,
                                                         GParamSpec *pspec);

Emits a "notify" signal for the property specified by pspec on object.

This function omits the property name lookup, hence it is faster than g_object_notify().

One way to avoid using g_object_notify() from within the class that registered the properties, and using g_object_notify_by_pspec() instead, is to store the GParamSpec used with g_object_class_install_property() inside a static array, e.g.:

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enum
  {
    PROP_0,
    PROP_FOO,
    PROP_LAST
  };

  static GParamSpec *properties[PROP_LAST];

  static void
  my_object_class_init (MyObjectClass *klass)
  {
    properties[PROP_FOO] = g_param_spec_int ("foo", "Foo", "The foo",
                                             0, 100,
                                             50,
                                             G_PARAM_READWRITE);
    g_object_class_install_property (gobject_class,
                                     PROP_FOO,
                                     properties[PROP_FOO]);
  }

and then notify a change on the "foo" property with:

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g_object_notify_by_pspec (self, properties[PROP_FOO]);

Since 2.26

g_object_freeze_notify ()

void                g_object_freeze_notify              (GObject *object);

Increases the freeze count on object. If the freeze count is non-zero, the emission of "notify" signals on object is stopped. The signals are queued until the freeze count is decreased to zero. Duplicate notifications are squashed so that at most one "notify" signal is emitted for each property modified while the object is frozen.

This is necessary for accessors that modify multiple properties to prevent premature notification while the object is still being modified.

g_object_thaw_notify ()

void                g_object_thaw_notify                (GObject *object);

Reverts the effect of a previous call to g_object_freeze_notify(). The freeze count is decreased on object and when it reaches zero, queued "notify" signals are emitted.

Duplicate notifications for each property are squashed so that at most one "notify" signal is emitted for each property.

It is an error to call this function when the freeze count is zero.

g_object_get_data ()

gpointer            g_object_get_data                   (GObject *object,
                                                         const gchar *key);

Gets a named field from the objects table of associations (see g_object_set_data()).

g_object_set_data ()

void                g_object_set_data                   (GObject *object,
                                                         const gchar *key,
                                                         gpointer 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.

g_object_set_data_full ()

void                g_object_set_data_full              (GObject *object,
                                                         const gchar *key,
                                                         gpointer data,
                                                         GDestroyNotify destroy);

Like g_object_set_data() except it adds notification for when the association is destroyed, either by setting it to a different value or when the object is destroyed.

Note that the destroy callback is not called if data is NULL.

g_object_steal_data ()

gpointer            g_object_steal_data                 (GObject *object,
                                                         const gchar *key);

Remove a specified datum from the object's data associations, without invoking the association's destroy handler.

g_object_dup_data ()

gpointer            g_object_dup_data                   (GObject *object,
                                                         const gchar *key,
                                                         GDuplicateFunc dup_func,
                                                         gpointer user_data);

This is a variant of g_object_get_data() which returns a 'duplicate' of the value. dup_func defines the meaning of 'duplicate' in this context, it could e.g. take a reference on a ref-counted object.

If the key is not set on the object then dup_func will be called with a NULL argument.

Note that dup_func is called while user data of object is locked.

This function can be useful to avoid races when multiple threads are using object data on the same key on the same object.

Since 2.34

g_object_replace_data ()

gboolean            g_object_replace_data               (GObject *object,
                                                         const gchar *key,
                                                         gpointer oldval,
                                                         gpointer newval,
                                                         GDestroyNotify destroy,
                                                         GDestroyNotify *old_destroy);

Compares the user data for the key key on object with oldval, and if they are the same, replaces oldval with newval.

This is like a typical atomic compare-and-exchange operation, for user data on an object.

If the previous value was replaced then ownership of the old value (oldval) is passed to the caller, including the registred destroy notify for it (passed out in old_destroy). Its up to the caller to free this as he wishes, which may or may not include using old_destroy as sometimes replacement should not destroy the object in the normal way.

Return: TRUE if the existing value for key was replaced by newval, FALSE otherwise.

Since 2.34

g_object_get_qdata ()

gpointer            g_object_get_qdata                  (GObject *object,
                                                         GQuark quark);

This function gets back user data pointers stored via g_object_set_qdata().

g_object_set_qdata ()

void                g_object_set_qdata                  (GObject *object,
                                                         GQuark quark,
                                                         gpointer data);

This sets an opaque, named pointer on an object. The name is specified through a GQuark (retrived e.g. via g_quark_from_static_string()), and the pointer can be gotten back from the object with g_object_get_qdata() until the object is finalized. Setting a previously set user data pointer, overrides (frees) the old pointer set, using NULL as pointer essentially removes the data stored.

g_object_set_qdata_full ()

void                g_object_set_qdata_full             (GObject *object,
                                                         GQuark quark,
                                                         gpointer data,
                                                         GDestroyNotify destroy);

This function works like g_object_set_qdata(), but in addition, a void (*destroy) (gpointer) function may be specified which is called with data as argument when the object is finalized, or the data is being overwritten by a call to g_object_set_qdata() with the same quark.

g_object_steal_qdata ()

gpointer            g_object_steal_qdata                (GObject *object,
                                                         GQuark quark);

This function gets back user data pointers stored via g_object_set_qdata() and removes the data from object without invoking its destroy() function (if any was set). Usually, calling this function is only required to update user data pointers with a destroy notifier, for example:

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void
object_add_to_user_list (GObject     *object,
                         const gchar *new_string)
{
  // the quark, naming the object data
  GQuark quark_string_list = g_quark_from_static_string ("my-string-list");
  // retrive the old string list
  GList *list = g_object_steal_qdata (object, quark_string_list);

  // prepend new string
  list = g_list_prepend (list, g_strdup (new_string));
  // this changed 'list', so we need to set it again
  g_object_set_qdata_full (object, quark_string_list, list, free_string_list);
}
static void
free_string_list (gpointer data)
{
  GList *node, *list = data;

  for (node = list; node; node = node->next)
    g_free (node->data);
  g_list_free (list);
}

Using g_object_get_qdata() in the above example, instead of g_object_steal_qdata() would have left the destroy function set, and thus the partial string list would have been freed upon g_object_set_qdata_full().

g_object_dup_qdata ()

gpointer            g_object_dup_qdata                  (GObject *object,
                                                         GQuark quark,
                                                         GDuplicateFunc dup_func,
                                                         gpointer user_data);

This is a variant of g_object_get_qdata() which returns a 'duplicate' of the value. dup_func defines the meaning of 'duplicate' in this context, it could e.g. take a reference on a ref-counted object.

If the quark is not set on the object then dup_func will be called with a NULL argument.

Note that dup_func is called while user data of object is locked.

This function can be useful to avoid races when multiple threads are using object data on the same key on the same object.

Since 2.34

g_object_replace_qdata ()

gboolean            g_object_replace_qdata              (GObject *object,
                                                         GQuark quark,
                                                         gpointer oldval,
                                                         gpointer newval,
                                                         GDestroyNotify destroy,
                                                         GDestroyNotify *old_destroy);

Compares the user data for the key quark on object with oldval, and if they are the same, replaces oldval with newval.

This is like a typical atomic compare-and-exchange operation, for user data on an object.

If the previous value was replaced then ownership of the old value (oldval) is passed to the caller, including the registred destroy notify for it (passed out in old_destroy). Its up to the caller to free this as he wishes, which may or may not include using old_destroy as sometimes replacement should not destroy the object in the normal way.

Return: TRUE if the existing value for quark was replaced by newval, FALSE otherwise.

Since 2.34

g_object_set_property ()

void                g_object_set_property               (GObject *object,
                                                         const gchar *property_name,
                                                         const GValue *value);

Sets a property on an object.

g_object_get_property ()

void                g_object_get_property               (GObject *object,
                                                         const gchar *property_name,
                                                         GValue *value);

Gets a property of an object. value must have been initialized to the expected type of the property (or a type to which the expected type can be transformed) using g_value_init().

In general, a copy is made of the property contents and the caller is responsible for freeing the memory by calling g_value_unset().

Note that g_object_get_property() is really intended for language bindings, g_object_get() is much more convenient for C programming.

g_object_new_valist ()

GObject *           g_object_new_valist                 (GType object_type,
                                                         const gchar *first_property_name,
                                                         va_list var_args);

Creates a new instance of a GObject subtype and sets its properties.

Construction parameters (see G_PARAM_CONSTRUCT, G_PARAM_CONSTRUCT_ONLY) which are not explicitly specified are set to their default values.

g_object_set_valist ()

void                g_object_set_valist                 (GObject *object,
                                                         const gchar *first_property_name,
                                                         va_list var_args);

Sets properties on an object.

g_object_get_valist ()

void                g_object_get_valist                 (GObject *object,
                                                         const gchar *first_property_name,
                                                         va_list var_args);

Gets properties of an object.

In general, a copy is made of the property contents and the caller is responsible for freeing the memory in the appropriate manner for the type, for instance by calling g_free() or g_object_unref().

See g_object_get().

g_object_watch_closure ()

void                g_object_watch_closure              (GObject *object,
                                                         GClosure *closure);

This function essentially limits the life time of the closure to the life time of the object. That is, when the object is finalized, the closure is invalidated by calling g_closure_invalidate() on it, in order to prevent invocations of the closure with a finalized (nonexisting) object. Also, g_object_ref() and g_object_unref() are added as marshal guards to the closure, to ensure that an extra reference count is held on object during invocation of the closure. Usually, this function will be called on closures that use this object as closure data.

g_object_run_dispose ()

void                g_object_run_dispose                (GObject *object);

Releases all references to other objects. This can be used to break reference cycles.

This functions should only be called from object system implementations.

G_OBJECT_WARN_INVALID_PROPERTY_ID()

#define             G_OBJECT_WARN_INVALID_PROPERTY_ID(object, property_id, pspec)

This macro should be used to emit a standard warning about unexpected properties in set_property() and get_property() implementations.

GWeakRef

typedef struct {
} GWeakRef;

A structure containing a weak reference to a GObject. It can either be empty (i.e. point to NULL), or point to an object for as long as at least one "strong" reference to that object exists. Before the object's GObjectClass.dispose method is called, every GWeakRef associated with becomes empty (i.e. points to NULL).

Like GValue, GWeakRef can be statically allocated, stack- or heap-allocated, or embedded in larger structures.

Unlike g_object_weak_ref() and g_object_add_weak_pointer(), this weak reference is thread-safe: converting a weak pointer to a reference is atomic with respect to invalidation of weak pointers to destroyed objects.

If the object's GObjectClass.dispose method results in additional references to the object being held, any GWeakRefs taken before it was disposed will continue to point to NULL. If GWeakRefs are taken after the object is disposed and re-referenced, they will continue to point to it until its refcount goes back to zero, at which point they too will be invalidated.

g_weak_ref_init ()

void                g_weak_ref_init                     (GWeakRef *weak_ref,
                                                         gpointer object);

Initialise a non-statically-allocated GWeakRef.

This function also calls g_weak_ref_set() with object on the freshly-initialised weak reference.

This function should always be matched with a call to g_weak_ref_clear(). It is not necessary to use this function for a GWeakRef in static storage because it will already be properly initialised. Just use g_weak_ref_set() directly.

Since 2.32

g_weak_ref_clear ()

void                g_weak_ref_clear                    (GWeakRef *weak_ref);

Frees resources associated with a non-statically-allocated GWeakRef. After this call, the GWeakRef is left in an undefined state.

You should only call this on a GWeakRef that previously had g_weak_ref_init() called on it.

Since 2.32

g_weak_ref_get ()

gpointer            g_weak_ref_get                      (GWeakRef *weak_ref);

If weak_ref is not empty, atomically acquire a strong reference to the object it points to, and return that reference.

This function is needed because of the potential race between taking the pointer value and g_object_ref() on it, if the object was losing its last reference at the same time in a different thread.

The caller should release the resulting reference in the usual way, by using g_object_unref().

Since 2.32

g_weak_ref_set ()

void                g_weak_ref_set                      (GWeakRef *weak_ref,
                                                         gpointer object);

Change the object to which weak_ref points, or set it to NULL.

You must own a strong reference on object while calling this function.

Since 2.32

The "notify" signal

void                user_function                      (GObject    *gobject,
                                                        GParamSpec *pspec,
                                                        gpointer    user_data)      : No Hooks

The notify signal is emitted on an object when one of its properties has been changed. Note that getting this signal doesn't guarantee that the value of the property has actually changed, it may also be emitted when the setter for the property is called to reinstate the previous value.

This signal is typically used to obtain change notification for a single property, by specifying the property name as a detail in the g_signal_connect() call, like this:

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2
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g_signal_connect (text_view->buffer, "notify::paste-target-list",
                  G_CALLBACK (gtk_text_view_target_list_notify),
                  text_view)

It is important to note that you must use canonical parameter names as detail strings for the notify signal.