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/*
* e-extensible.c
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) version 3.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with the program; if not, see <http://www.gnu.org/licenses/>
*
*/
/**
* SECTION: e-extensible
* @short_description: an interface for extending objects
* @include: e-util/e-extensible.h
*
* #EExtension objects can be tacked on to any #GObject instance that
* implements the #EExtensible interface. A #GObject type can be made
* extensible in two steps:
*
* 1. Add the #EExtensible interface when registering the #GType.
* There are no methods to implement.
*
* <informalexample>
* <programlisting>
* #include <e-util/e-extensible.h>
*
* G_DEFINE_TYPE_WITH_CODE (
* ECustomWidget, e_custom_widget, GTK_TYPE_WIDGET,
* G_IMPLEMENT_INTERFACE (E_TYPE_EXTENSIBLE, NULL))
* </programlisting>
* </informalexample>
*
* 2. Load extensions for the class at some point during #GObject
* initialization. Generally this should be done toward the end of
* the initialization code, so extensions get a fully initialized
* object to work with.
*
* <informalexample>
* <programlisting>
* static void
* e_custom_widget_init (ECustomWidget *widget)
* {
* Initialization code goes here...
*
* e_extensible_load_extensions (E_EXTENSIBLE (widget));
* }
* </programlisting>
* </informalexample>
**/
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include "e-extensible.h"
#include <e-util/e-util.h>
#include <e-util/e-extension.h>
#define IS_AN_EXTENSION_TYPE(type) \
(g_type_is_a ((type), E_TYPE_EXTENSION))
static GQuark extensible_quark;
G_DEFINE_INTERFACE (
EExtensible,
e_extensible,
G_TYPE_OBJECT)
static GPtrArray *
extensible_get_extensions (EExtensible *extensible)
{
return g_object_get_qdata (G_OBJECT (extensible), extensible_quark);
}
static void
extensible_load_extension (GType extension_type,
EExtensible *extensible)
{
EExtensionClass *extension_class;
GType extensible_type;
GPtrArray *extensions;
EExtension *extension;
extensible_type = G_OBJECT_TYPE (extensible);
extension_class = g_type_class_ref (extension_type);
/* Only load extensions that extend the given extensible object. */
if (g_type_is_a (extensible_type, extension_class->extensible_type)) {
extension = g_object_new (
extension_type, "extensible", extensible, NULL);
extensions = extensible_get_extensions (extensible);
g_ptr_array_add (extensions, extension);
g_type_class_unref (extension_class);
} else {
/* keep the class referenced forever, later may anyone need it anyway,
and unref it may mean module unload, which breaks static strings
in GType */
}
}
static void
e_extensible_default_init (EExtensibleInterface *interface)
{
extensible_quark = g_quark_from_static_string ("e-extensible-quark");
}
/**
* e_extensible_load_extensions:
* @extensible: an #EExtensible
*
* Creates an instance of all instantiable subtypes of #EExtension which
* target the class of @extensible. The lifetimes of these newly created
* #EExtension objects are bound to @extensible such that they are finalized
* when @extensible is finalized.
**/
void
e_extensible_load_extensions (EExtensible *extensible)
{
GPtrArray *extensions;
g_return_if_fail (E_IS_EXTENSIBLE (extensible));
if (extensible_get_extensions (extensible) != NULL)
return;
extensions = g_ptr_array_new_with_free_func (
(GDestroyNotify) g_object_unref);
g_object_set_qdata_full (
G_OBJECT (extensible), extensible_quark,
extensions, (GDestroyNotify) g_ptr_array_unref);
e_type_traverse (
E_TYPE_EXTENSION, (ETypeFunc)
extensible_load_extension, extensible);
}
/**
* e_extensible_list_extensions:
* @extensible: an #EExtensible
* @extension_type: the type of extensions to list
*
* Returns a list of #EExtension objects bound to @extensible whose
* types are ancestors of @extension_type. For a complete list of
* extension objects bound to @extensible, pass %E_TYPE_EXTENSION.
*
* The list itself should be freed with g_list_free(). The extension
* objects are owned by @extensible and should not be unreferenced.
*
* Returns: a list of extension objects derived from @extension_type
**/
GList *
e_extensible_list_extensions (EExtensible *extensible,
GType extension_type)
{
GPtrArray *extensions;
GList *list = NULL;
guint ii;
g_return_val_if_fail (E_IS_EXTENSIBLE (extensible), NULL);
g_return_val_if_fail (IS_AN_EXTENSION_TYPE (extension_type), NULL);
e_extensible_load_extensions (extensible);
extensions = extensible_get_extensions (extensible);
g_return_val_if_fail (extensions != NULL, NULL);
for (ii = 0; ii < extensions->len; ii++) {
GObject *object;
object = g_ptr_array_index (extensions, ii);
if (g_type_is_a (G_OBJECT_TYPE (object), extension_type))
list = g_list_prepend (list, object);
}
return g_list_reverse (list);
}
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