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/* GObject - GLib Type, Object, Parameter and Signal Library
* Copyright (C) 2000 Red Hat, Inc.
*
* 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.
*/
#include "config.h"
#include "gtypeplugin.h"
/**
* SECTION:gtypeplugin
* @short_description: An interface for dynamically loadable types
* @see_also: #GTypeModule and g_type_register_dynamic().
* @title: GTypePlugin
*
* The GObject type system supports dynamic loading of types. The
* #GTypePlugin interface is used to handle the lifecycle of
* dynamically loaded types. It goes as follows:
*
* <orderedlist>
* <listitem><para>
* The type is initially introduced (usually upon loading the module
* the first time, or by your main application that knows what modules
* introduces what types), like this:
* |[
* new_type_id = g_type_register_dynamic (parent_type_id,
* "TypeName",
* new_type_plugin,
* type_flags);
* ]|
* where <literal>new_type_plugin</literal> is an implementation of the
* #GTypePlugin interface.
* </para></listitem>
* <listitem><para>
* The type's implementation is referenced, e.g. through
* g_type_class_ref() or through g_type_create_instance() (this is
* being called by g_object_new()) or through one of the above done on
* a type derived from <literal>new_type_id</literal>.
* </para></listitem>
* <listitem><para>
* This causes the type system to load the type's implementation by calling
* g_type_plugin_use() and g_type_plugin_complete_type_info() on
* <literal>new_type_plugin</literal>.
* </para></listitem>
* <listitem><para>
* At some point the type's implementation isn't required anymore, e.g. after
* g_type_class_unref() or g_type_free_instance() (called when the reference
* count of an instance drops to zero).
* </para></listitem>
* <listitem><para>
* This causes the type system to throw away the information retrieved from
* g_type_plugin_complete_type_info() and then it calls
* g_type_plugin_unuse() on <literal>new_type_plugin</literal>.
* </para></listitem>
* <listitem><para>
* Things may repeat from the second step.
* </para></listitem>
* </orderedlist>
*
* So basically, you need to implement a #GTypePlugin type that
* carries a use_count, once use_count goes from zero to one, you need
* to load the implementation to successfully handle the upcoming
* g_type_plugin_complete_type_info() call. Later, maybe after
* succeeding use/unuse calls, once use_count drops to zero, you can
* unload the implementation again. The type system makes sure to call
* g_type_plugin_use() and g_type_plugin_complete_type_info() again
* when the type is needed again.
*
* #GTypeModule is an implementation of #GTypePlugin that already
* implements most of this except for the actual module loading and
* unloading. It even handles multiple registered types per module.
*/
/* --- functions --- */
GType
g_type_plugin_get_type (void)
{
static GType type_plugin_type = 0;
if (!type_plugin_type)
{
const GTypeInfo type_plugin_info = {
sizeof (GTypePluginClass),
NULL, /* base_init */
NULL, /* base_finalize */
};
type_plugin_type = g_type_register_static (G_TYPE_INTERFACE, g_intern_static_string ("GTypePlugin"), &type_plugin_info, 0);
}
return type_plugin_type;
}
/**
* g_type_plugin_use:
* @plugin: a #GTypePlugin
*
* Calls the @use_plugin function from the #GTypePluginClass of
* @plugin. There should be no need to use this function outside of
* the GObject type system itself.
*/
void
g_type_plugin_use (GTypePlugin *plugin)
{
GTypePluginClass *iface;
g_return_if_fail (G_IS_TYPE_PLUGIN (plugin));
iface = G_TYPE_PLUGIN_GET_CLASS (plugin);
iface->use_plugin (plugin);
}
/**
* g_type_plugin_unuse:
* @plugin: a #GTypePlugin
*
* Calls the @unuse_plugin function from the #GTypePluginClass of
* @plugin. There should be no need to use this function outside of
* the GObject type system itself.
*/
void
g_type_plugin_unuse (GTypePlugin *plugin)
{
GTypePluginClass *iface;
g_return_if_fail (G_IS_TYPE_PLUGIN (plugin));
iface = G_TYPE_PLUGIN_GET_CLASS (plugin);
iface->unuse_plugin (plugin);
}
/**
* g_type_plugin_complete_type_info:
* @plugin: a #GTypePlugin
* @g_type: the #GType whose info is completed
* @info: the #GTypeInfo struct to fill in
* @value_table: the #GTypeValueTable to fill in
*
* Calls the @complete_type_info function from the #GTypePluginClass of @plugin.
* There should be no need to use this function outside of the GObject
* type system itself.
*/
void
g_type_plugin_complete_type_info (GTypePlugin *plugin,
GType g_type,
GTypeInfo *info,
GTypeValueTable *value_table)
{
GTypePluginClass *iface;
g_return_if_fail (G_IS_TYPE_PLUGIN (plugin));
g_return_if_fail (info != NULL);
g_return_if_fail (value_table != NULL);
iface = G_TYPE_PLUGIN_GET_CLASS (plugin);
iface->complete_type_info (plugin,
g_type,
info,
value_table);
}
/**
* g_type_plugin_complete_interface_info:
* @plugin: the #GTypePlugin
* @instance_type: the #GType of an instantiable type to which the interface
* is added
* @interface_type: the #GType of the interface whose info is completed
* @info: the #GInterfaceInfo to fill in
*
* Calls the @complete_interface_info function from the
* #GTypePluginClass of @plugin. There should be no need to use this
* function outside of the GObject type system itself.
*/
void
g_type_plugin_complete_interface_info (GTypePlugin *plugin,
GType instance_type,
GType interface_type,
GInterfaceInfo *info)
{
GTypePluginClass *iface;
g_return_if_fail (G_IS_TYPE_PLUGIN (plugin));
g_return_if_fail (info != NULL);
iface = G_TYPE_PLUGIN_GET_CLASS (plugin);
iface->complete_interface_info (plugin,
instance_type,
interface_type,
info);
}
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