glib/tests/gobject/singleton.c

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/* GObject - GLib Type, Object, Parameter and Signal Library
* Copyright (C) 2006 Imendio AB
*
* This library 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) any later version.
*
* This library 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 this library; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place, Suite 330,
* Boston, MA 02111-1307, USA.
*/
#undef G_LOG_DOMAIN
#define G_LOG_DOMAIN "TestSingleton"
#include <glib-object.h>
#include <string.h>
/* --- MySingleton class --- */
typedef struct {
GObject parent_instance;
} MySingleton;
typedef struct {
GObjectClass parent_class;
} MySingletonClass;
#define MY_TYPE_SINGLETON (my_singleton_get_type ())
#define MY_SINGLETON(o) (G_TYPE_CHECK_INSTANCE_CAST ((o), MY_TYPE_SINGLETON, MySingleton))
#define MY_IS_SINGLETON(o) (G_TYPE_CHECK_INSTANCE_TYPE ((o), MY_TYPE_SINGLETON))
#define MY_SINGLETON_CLASS(c) (G_TYPE_CHECK_CLASS_CAST ((c), MY_TYPE_SINGLETON, MySingletonClass))
#define MY_IS_SINGLETON_CLASS(c) (G_TYPE_CHECK_CLASS_TYPE ((c), MY_TYPE_SINGLETON))
#define MY_SINGLETON_GET_CLASS(o) (G_TYPE_INSTANCE_GET_CLASS ((o), MY_TYPE_SINGLETON, MySingletonClass))
G_DEFINE_TYPE (MySingleton, my_singleton, G_TYPE_OBJECT);
static MySingleton *the_one_and_only = NULL;
/* --- methods --- */
static GObject*
my_singleton_constructor (GType type,
guint n_construct_properties,
GObjectConstructParam *construct_properties)
{
if (the_one_and_only)
return g_object_ref (the_one_and_only);
else
return G_OBJECT_CLASS (my_singleton_parent_class)->constructor (type, n_construct_properties, construct_properties);
}
static void
my_singleton_init (MySingleton *self)
{
g_assert (the_one_and_only == NULL);
the_one_and_only = self;
}
static void
my_singleton_class_init (MySingletonClass *klass)
{
G_OBJECT_CLASS (klass)->constructor = my_singleton_constructor;
}
/* --- test program --- */
int
main (int argc,
char *argv[])
{
MySingleton *singleton, *obj;
g_type_init_with_debug_flags (G_TYPE_DEBUG_OBJECTS | G_TYPE_DEBUG_SIGNALS);
/* create the singleton */
singleton = g_object_new (MY_TYPE_SINGLETON, NULL);
g_assert (singleton != NULL);
/* assert _singleton_ creation */
obj = g_object_new (MY_TYPE_SINGLETON, NULL);
g_assert (singleton == obj);
g_object_unref (obj);
/* shutdown */
g_object_unref (singleton);
return 0;
}