/* 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 2.1 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, see <http://www.gnu.org/licenses/>.

 */

#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;

static GType my_singleton_get_type (void);

#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 (G_OBJECT (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;

  /* 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;

}