tests/gobject/singleton.c

   1 /* GObject - GLib Type, Object, Parameter and Signal Library
   2  * Copyright (C) 2006 Imendio AB
   3  *
   4  * This library is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU Lesser General Public
   6  * License as published by the Free Software Foundation; either
   7  * version 2.1 of the License, or (at your option) any later version.
   8  *
   9  * This library is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * Lesser General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU Lesser General
  15  * Public License along with this library; if not, see <http://www.gnu.org/licenses/>.
  16  */
  17 #undef  G_LOG_DOMAIN
  18 #define G_LOG_DOMAIN "TestSingleton"
  19 #include <glib-object.h>
  20 #include <string.h>
  21
  22 /* --- MySingleton class --- */
  23 typedef struct {
  24   GObject parent_instance;
  25 } MySingleton;
  26 typedef struct {
  27   GObjectClass parent_class;
  28 } MySingletonClass;
  29
  30 static GType my_singleton_get_type (void);
  31 #define MY_TYPE_SINGLETON         (my_singleton_get_type ())
  32 #define MY_SINGLETON(o)           (G_TYPE_CHECK_INSTANCE_CAST ((o), MY_TYPE_SINGLETON, MySingleton))
  33 #define MY_IS_SINGLETON(o)        (G_TYPE_CHECK_INSTANCE_TYPE ((o), MY_TYPE_SINGLETON))
  34 #define MY_SINGLETON_CLASS(c)     (G_TYPE_CHECK_CLASS_CAST ((c), MY_TYPE_SINGLETON, MySingletonClass))
  35 #define MY_IS_SINGLETON_CLASS(c)  (G_TYPE_CHECK_CLASS_TYPE ((c), MY_TYPE_SINGLETON))
  36 #define MY_SINGLETON_GET_CLASS(o) (G_TYPE_INSTANCE_GET_CLASS ((o), MY_TYPE_SINGLETON, MySingletonClass))
  37
  38 G_DEFINE_TYPE (MySingleton, my_singleton, G_TYPE_OBJECT)
  39
  40 static MySingleton *the_one_and_only = NULL;
  41
  42 /* --- methods --- */
  43 static GObject*
  44 my_singleton_constructor (GType                  type,
  45                           guint                  n_construct_properties,
  46                           GObjectConstructParam *construct_properties)
  47 {
  48   if (the_one_and_only)
  49     return g_object_ref (G_OBJECT (the_one_and_only));
  50   else
  51     return G_OBJECT_CLASS (my_singleton_parent_class)->constructor (type, n_construct_properties, construct_properties);
  52 }
  53
  54 static void
  55 my_singleton_init (MySingleton *self)
  56 {
  57   g_assert (the_one_and_only == NULL);
  58   the_one_and_only = self;
  59 }
  60
  61 static void
  62 my_singleton_class_init (MySingletonClass *klass)
  63 {
  64   G_OBJECT_CLASS (klass)->constructor = my_singleton_constructor;
  65 }
  66
  67 /* --- test program --- */
  68 int
  69 main (int   argc,
  70       char *argv[])
  71 {
  72   MySingleton *singleton, *obj;
  73
  74   /* create the singleton */
  75   singleton = g_object_new (MY_TYPE_SINGLETON, NULL);
  76   g_assert (singleton != NULL);
  77   /* assert _singleton_ creation */
  78   obj = g_object_new (MY_TYPE_SINGLETON, NULL);
  79   g_assert (singleton == obj);
  80   g_object_unref (obj);
  81   /* shutdown */
  82   g_object_unref (singleton);
  83   return 0;
  84 }