GObject.ObjectClass¶
Fields¶
Name |
Type |
Access |
Description |
---|---|---|---|
construct_properties |
[ |
r |
|
constructed |
r |
||
constructor |
r |
||
dispatch_properties_changed |
r |
||
dispose |
r |
||
finalize |
r |
||
flags |
r |
||
g_type_class |
r |
the parent class |
|
get_property |
r |
||
n_construct_properties |
r |
||
n_pspecs |
r |
||
notify |
r |
||
pdummy |
[ |
r |
|
pspecs |
r |
||
set_property |
r |
Methods¶
|
|
|
|
|
|
|
Details¶
- class GObject.ObjectClass¶
The class structure for the
GObject.Object
type.// Example of implementing a singleton using a constructor. 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; }
- find_property(property_name)¶
- Parameters:
property_name (
str
) – the name of the property to look up- Returns:
the
GObject.ParamSpec
for the property, orNone
if the class doesn’t have a property of that name- Return type:
Looks up the
GObject.ParamSpec
for a property of a class.
- install_properties(pspecs)¶
- Parameters:
pspecs ([
GObject.ParamSpec
]) – theGObject.ParamSpecs
array defining the new properties
Installs new properties from an array of
GObject.ParamSpecs
.All properties should be installed during the class initializer. It is possible to install properties after that, but doing so is not recommend, and specifically, is not guaranteed to be thread-safe vs. use of properties on the same type on other threads.
The property id of each property is the index of each
GObject.ParamSpec
in the pspecs array.The property id of 0 is treated specially by
GObject.Object
and it should not be used to store aGObject.ParamSpec
.This function should be used if you plan to use a static array of
GObject.ParamSpecs
andGObject.Object.notify_by_pspec
(). For instance, this class initialization:typedef enum { PROP_FOO = 1, PROP_BAR, N_PROPERTIES } MyObjectProperty; 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 | G_PARAM_STATIC_STRINGS); obj_properties[PROP_BAR] = g_param_spec_string ("bar", "Bar", "Bar", NULL, G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS); gobject_class->set_property = my_object_set_property; gobject_class->get_property = my_object_get_property; g_object_class_install_properties (gobject_class, G_N_ELEMENTS (obj_properties), obj_properties); }
allows calling
GObject.Object.notify_by_pspec
() to notify of property changes: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]); } }
New in version 2.26.
- install_property(property_id, pspec)¶
- Parameters:
property_id (
int
) – the id for the new propertypspec (
GObject.ParamSpec
) – theGObject.ParamSpec
for the new property
Installs a new property.
All properties should be installed during the class initializer. It is possible to install properties after that, but doing so is not recommend, and specifically, is not guaranteed to be thread-safe vs. use of properties on the same type on other threads.
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.
- list_properties()¶
- Returns:
an array of
GObject.ParamSpec
which should be freed after use- Return type:
Get an array of
GObject.ParamSpec
for all properties of a class.
- override_property(property_id, name)¶
- Parameters:
Registers property_id as referring to a property with the name name in a parent class or in an interface implemented by self. This allows this class to “override” a property implementation in a parent class or to provide the implementation of a property from an interface.
Internally, overriding is implemented by creating a property of type
GObject.ParamSpecOverride
; generally operations that query the properties of the object class, such asGObject.ObjectClass.find_property
() orGObject.ObjectClass.list_properties
() will return the overridden property. However, in one case, the construct_properties argument of the constructor virtual function, theGObject.ParamSpecOverride
is passed instead, so that the param_id field of theGObject.ParamSpec
will be correct. For virtually all uses, this makes no difference. If you need to get the overridden property, you can callGObject.ParamSpec.get_redirect_target
().New in version 2.4.