Gio-2.0 ▶ Gio ▶ SettingsBackendAbstract

Creates a binding between source_property on source and target_property on target.

Whenever the source_property is changed the target_property is updated using the same value. For instance:

  g_object_bind_property (action, "active", widget, "sensitive", 0);
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Will result in the "sensitive" property of the widget GObject.Object instance to be updated with the same value of the "active" property of the action GObject.Object instance.

If flags contains GObject.BindingFlags.BIDIRECTIONAL then the binding will be mutual: if target_property on target changes then the source_property on source will be updated as well.

The binding will automatically be removed when either the source or the target instances are finalized. To remove the binding without affecting the source and the target you can just call g_object_unref() on the returned GObject.Binding instance.

Removing the binding by calling g_object_unref() on it must only be done if the binding, source and target are only used from a single thread and it is clear that both source and target outlive the binding. Especially it is not safe to rely on this if the binding, source or target can be finalized from different threads. Keep another reference to the binding and use g_binding_unbind() instead to be on the safe side.

A GObject.Object can have multiple bindings.

Complete version of g_object_bind_property().

Creates a binding between source_property on source and target_property on target, allowing you to set the transformation functions to be used by the binding.

If flags contains GObject.BindingFlags.BIDIRECTIONAL then the binding will be mutual: if target_property on target changes then the source_property on source will be updated as well. The transform_from function is only used in case of bidirectional bindings, otherwise it will be ignored

The binding will automatically be removed when either the source or the target instances are finalized. This will release the reference that is being held on the GObject.Binding instance; if you want to hold on to the GObject.Binding instance, you will need to hold a reference to it.

To remove the binding, call g_binding_unbind().

A GObject.Object can have multiple bindings.

The same user_data parameter will be used for both transform_to and transform_from transformation functions; the notify function will be called once, when the binding is removed. If you need different data for each transformation function, please use g_object_bind_property_with_closures() instead.

Creates a binding between source_property on source and target_property on target, allowing you to set the transformation functions to be used by the binding.

This function is the language bindings friendly version of g_object_bind_property_full(), using GClosures instead of function pointers.

Blocks a handler of an instance so it will not be called during any signal emissions

Disconnects a handler from an instance so it will not be called during any future or currently ongoing emissions of the signal it has been connected to.

This function is intended for GObject.Object implementations to re-enforce a [floating][floating-ref] 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().

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 GObject.Object::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.

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

Gets a property of an object.

The value can be:

• an empty GObject.Value initialized by G_VALUE_INIT, which will be automatically initialized with the expected type of the property (since GLib 2.60)
• a GObject.Value initialized with the expected type of the property
• a GObject.Value initialized with a type to which the expected type of the property can be transformed

In general, a copy is made of the property contents and the caller is responsible for freeing the memory by calling GObject.Value.unset.

Note that GObject.Object.get_property is really intended for language bindings, GObject.Object.get is much more convenient for C programming.

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

Gets n_properties properties for an object. Obtained properties will be set to values. All properties must be valid. Warnings will be emitted and undefined behaviour may result if invalid properties are passed in.

Checks whether object has a [floating][floating-ref] reference.

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.

Note that emission of the notify signal may be blocked with g_object_freeze_notify(). In this case, the signal emissions are queued and will be emitted (in reverse order) when g_object_thaw_notify() is called.

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.:

  typedef enum
  {
    PROP_FOO = 1,
    PROP_LAST
  } MyObjectProperty;

  static GParamSpec *properties[PROP_LAST];

  static void
  my_object_class_init (MyObjectClass *klass)
  {
    properties[PROP_FOO] = g_param_spec_int ("foo", NULL, NULL,
                                             0, 100,
                                             50,
                                             G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS);
    g_object_class_install_property (gobject_class,
                                     PROP_FOO,
                                     properties[PROP_FOO]);
  }
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and then notify a change on the "foo" property with:

  g_object_notify_by_pspec (self, properties[PROP_FOO]);
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Increases the reference count of object.

Since GLib 2.56, if GLIB_VERSION_MAX_ALLOWED is 2.56 or greater, the type of object will be propagated to the return type (using the GCC typeof() extension), so any casting the caller needs to do on the return type must be explicit.

Increase the reference count of object, and possibly remove the [floating][floating-ref] 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 GLib 2.56, the type of object will be propagated to the return type under the same conditions as for g_object_ref().

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

This function should only be called from object system implementations.

Sets multiple properties of an object at once. The properties argument should be a dictionary mapping property names to values.

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.

Internally, the key is converted to a GLib.Quark using g_quark_from_string(). This means a copy of key is kept permanently (even after object has been finalized) — so it is recommended to only use a small, bounded set of values for key in your program, to avoid the GLib.Quark storage growing unbounded.

Sets a property on an object.

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

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:

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");
  // retrieve 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);
}
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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().

Stops a signal's emission by the given signal name. This will prevent the default handler and any subsequent signal handlers from being invoked.

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 GObject.Object::notify signal is emitted for each property, in the reverse order in which they have been queued.

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

Unblocks a handler so it will be called again during any signal emissions

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

If the pointer to the GObject.Object may be reused in future (for example, if it is an instance variable of another object), it is recommended to clear the pointer to null rather than retain a dangling pointer to a potentially invalid GObject.Object instance. Use g_clear_object() for this.

the constructed function is called by g_object_new() as the final step of the object creation process. At the point of the call, all construction properties have been set on the object. The purpose of this call is to allow for object initialisation steps that can only be performed after construction properties have been set. constructed implementors should chain up to the constructed call of their parent class to allow it to complete its initialisation.

emits property change notification for a bunch of properties. Overriding dispatch_properties_changed should be rarely needed.

the dispose function is supposed to drop all references to other objects, but keep the instance otherwise intact, so that client method invocations still work. It may be run multiple times (due to reference loops). Before returning, dispose should chain up to the dispose method of the parent class.

instance finalization function, should finish the finalization of the instance begun in dispose and chain up to the finalize method of the parent class.

the generic getter for all properties of this type. Should be overridden for every type with properties.

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.

Note that emission of the notify signal may be blocked with g_object_freeze_notify(). In this case, the signal emissions are queued and will be emitted (in reverse order) when g_object_thaw_notify() is called.

the generic setter for all properties of this type. Should be overridden for every type with properties. If implementations of set_property don't emit property change notification explicitly, this will be done implicitly by the type system. However, if the notify signal is emitted explicitly, the type system will not emit it a second time.

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.

Find the GObject.ParamSpec 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().

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 GObject.ParamSpec, 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 GObject.TypeInfo.) It must not be called after after class_init has been called for any object types implementing this interface.

If pspec is a floating reference, it will be consumed.

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().