1/* GIO - GLib Input, Output and Streaming Library
2 *
3 * Copyright (C) 2009 Red Hat, Inc.
4 *
5 * This library is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU Lesser General Public
7 * License as published by the Free Software Foundation; either
8 * version 2.1 of the License, or (at your option) any later version.
9 *
10 * This library is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * Lesser General Public License for more details.
14 *
15 * You should have received a copy of the GNU Lesser General
16 * Public License along with this library; if not, see <http://www.gnu.org/licenses/>.
17 *
18 * Author: Alexander Larsson <alexl@redhat.com>
19 */
20
21#include "config.h"
22#include "ginitable.h"
23#include "glibintl.h"
24
25
26/**
27 * SECTION:ginitable
28 * @short_description: Failable object initialization interface
29 * @include: gio/gio.h
30 * @see_also: #GAsyncInitable
31 *
32 * #GInitable is implemented by objects that can fail during
33 * initialization. If an object implements this interface then
34 * it must be initialized as the first thing after construction,
35 * either via g_initable_init() or g_async_initable_init_async()
36 * (the latter is only available if it also implements #GAsyncInitable).
37 *
38 * If the object is not initialized, or initialization returns with an
39 * error, then all operations on the object except g_object_ref() and
40 * g_object_unref() are considered to be invalid, and have undefined
41 * behaviour. They will often fail with g_critical() or g_warning(), but
42 * this must not be relied on.
43 *
44 * Users of objects implementing this are not intended to use
45 * the interface method directly, instead it will be used automatically
46 * in various ways. For C applications you generally just call
47 * g_initable_new() directly, or indirectly via a foo_thing_new() wrapper.
48 * This will call g_initable_init() under the cover, returning %NULL and
49 * setting a #GError on failure (at which point the instance is
50 * unreferenced).
51 *
52 * For bindings in languages where the native constructor supports
53 * exceptions the binding could check for objects implementing %GInitable
54 * during normal construction and automatically initialize them, throwing
55 * an exception on failure.
56 */
57
58typedef GInitableIface GInitableInterface;
59G_DEFINE_INTERFACE (GInitable, g_initable, G_TYPE_OBJECT)
60
61static void
62g_initable_default_init (GInitableInterface *iface)
63{
64}
65
66/**
67 * g_initable_init:
68 * @initable: a #GInitable.
69 * @cancellable: optional #GCancellable object, %NULL to ignore.
70 * @error: a #GError location to store the error occurring, or %NULL to
71 * ignore.
72 *
73 * Initializes the object implementing the interface.
74 *
75 * This method is intended for language bindings. If writing in C,
76 * g_initable_new() should typically be used instead.
77 *
78 * The object must be initialized before any real use after initial
79 * construction, either with this function or g_async_initable_init_async().
80 *
81 * Implementations may also support cancellation. If @cancellable is not %NULL,
82 * then initialization can be cancelled by triggering the cancellable object
83 * from another thread. If the operation was cancelled, the error
84 * %G_IO_ERROR_CANCELLED will be returned. If @cancellable is not %NULL and
85 * the object doesn't support cancellable initialization the error
86 * %G_IO_ERROR_NOT_SUPPORTED will be returned.
87 *
88 * If the object is not initialized, or initialization returns with an
89 * error, then all operations on the object except g_object_ref() and
90 * g_object_unref() are considered to be invalid, and have undefined
91 * behaviour. See the [introduction][ginitable] for more details.
92 *
93 * Callers should not assume that a class which implements #GInitable can be
94 * initialized multiple times, unless the class explicitly documents itself as
95 * supporting this. Generally, a class’ implementation of init() can assume
96 * (and assert) that it will only be called once. Previously, this documentation
97 * recommended all #GInitable implementations should be idempotent; that
98 * recommendation was relaxed in GLib 2.54.
99 *
100 * If a class explicitly supports being initialized multiple times, it is
101 * recommended that the method is idempotent: multiple calls with the same
102 * arguments should return the same results. Only the first call initializes
103 * the object; further calls return the result of the first call.
104 *
105 * One reason why a class might need to support idempotent initialization is if
106 * it is designed to be used via the singleton pattern, with a
107 * #GObjectClass.constructor that sometimes returns an existing instance.
108 * In this pattern, a caller would expect to be able to call g_initable_init()
109 * on the result of g_object_new(), regardless of whether it is in fact a new
110 * instance.
111 *
112 * Returns: %TRUE if successful. If an error has occurred, this function will
113 * return %FALSE and set @error appropriately if present.
114 *
115 * Since: 2.22
116 */
117gboolean
118g_initable_init (GInitable *initable,
119 GCancellable *cancellable,
120 GError **error)
121{
122 GInitableIface *iface;
123
124 g_return_val_if_fail (G_IS_INITABLE (initable), FALSE);
125
126 iface = G_INITABLE_GET_IFACE (initable);
127
128 return (* iface->init) (initable, cancellable, error);
129}
130
131/**
132 * g_initable_new:
133 * @object_type: a #GType supporting #GInitable.
134 * @cancellable: optional #GCancellable object, %NULL to ignore.
135 * @error: a #GError location to store the error occurring, or %NULL to
136 * ignore.
137 * @first_property_name: (nullable): the name of the first property, or %NULL if no
138 * properties
139 * @...: the value if the first property, followed by and other property
140 * value pairs, and ended by %NULL.
141 *
142 * Helper function for constructing #GInitable object. This is
143 * similar to g_object_new() but also initializes the object
144 * and returns %NULL, setting an error on failure.
145 *
146 * Returns: (type GObject.Object) (transfer full): a newly allocated
147 * #GObject, or %NULL on error
148 *
149 * Since: 2.22
150 */
151gpointer
152g_initable_new (GType object_type,
153 GCancellable *cancellable,
154 GError **error,
155 const gchar *first_property_name,
156 ...)
157{
158 GObject *object;
159 va_list var_args;
160
161 va_start (var_args, first_property_name);
162 object = g_initable_new_valist (object_type,
163 first_property_name, var_args,
164 cancellable, error);
165 va_end (var_args);
166
167 return object;
168}
169
170/**
171 * g_initable_newv:
172 * @object_type: a #GType supporting #GInitable.
173 * @n_parameters: the number of parameters in @parameters
174 * @parameters: (array length=n_parameters): the parameters to use to construct the object
175 * @cancellable: optional #GCancellable object, %NULL to ignore.
176 * @error: a #GError location to store the error occurring, or %NULL to
177 * ignore.
178 *
179 * Helper function for constructing #GInitable object. This is
180 * similar to g_object_newv() but also initializes the object
181 * and returns %NULL, setting an error on failure.
182 *
183 * Returns: (type GObject.Object) (transfer full): a newly allocated
184 * #GObject, or %NULL on error
185 *
186 * Since: 2.22
187 * Deprecated: 2.54: Use g_object_new_with_properties() and
188 * g_initable_init() instead. See #GParameter for more information.
189 */
190G_GNUC_BEGIN_IGNORE_DEPRECATIONS
191gpointer
192g_initable_newv (GType object_type,
193 guint n_parameters,
194 GParameter *parameters,
195 GCancellable *cancellable,
196 GError **error)
197{
198 GObject *obj;
199
200 g_return_val_if_fail (G_TYPE_IS_INITABLE (object_type), NULL);
201
202 obj = g_object_newv (object_type, n_parameters, parameters);
203
204 if (!g_initable_init (G_INITABLE (obj), cancellable, error))
205 {
206 g_object_unref (object: obj);
207 return NULL;
208 }
209
210 return (gpointer)obj;
211}
212G_GNUC_END_IGNORE_DEPRECATIONS
213
214/**
215 * g_initable_new_valist:
216 * @object_type: a #GType supporting #GInitable.
217 * @first_property_name: the name of the first property, followed by
218 * the value, and other property value pairs, and ended by %NULL.
219 * @var_args: The var args list generated from @first_property_name.
220 * @cancellable: optional #GCancellable object, %NULL to ignore.
221 * @error: a #GError location to store the error occurring, or %NULL to
222 * ignore.
223 *
224 * Helper function for constructing #GInitable object. This is
225 * similar to g_object_new_valist() but also initializes the object
226 * and returns %NULL, setting an error on failure.
227 *
228 * Returns: (type GObject.Object) (transfer full): a newly allocated
229 * #GObject, or %NULL on error
230 *
231 * Since: 2.22
232 */
233GObject*
234g_initable_new_valist (GType object_type,
235 const gchar *first_property_name,
236 va_list var_args,
237 GCancellable *cancellable,
238 GError **error)
239{
240 GObject *obj;
241
242 g_return_val_if_fail (G_TYPE_IS_INITABLE (object_type), NULL);
243
244 obj = g_object_new_valist (object_type,
245 first_property_name,
246 var_args);
247
248 if (!g_initable_init (G_INITABLE (obj), cancellable, error))
249 {
250 g_object_unref (object: obj);
251 return NULL;
252 }
253
254 return obj;
255}
256

source code of gtk/subprojects/glib/gio/ginitable.c