mirror of https://gitee.com/openkylin/glib2.0.git
257 lines
8.9 KiB
C
257 lines
8.9 KiB
C
/* GIO - GLib Input, Output and Streaming Library
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*
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* Copyright (C) 2009 Red Hat, Inc.
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*
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* SPDX-License-Identifier: LGPL-2.1-or-later
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General
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* Public License along with this library; if not, see <http://www.gnu.org/licenses/>.
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*
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* Author: Alexander Larsson <alexl@redhat.com>
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*/
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#include "config.h"
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#include "ginitable.h"
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#include "glibintl.h"
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/**
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* GInitable:
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*
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* `GInitable` is implemented by objects that can fail during
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* initialization. If an object implements this interface then
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* it must be initialized as the first thing after construction,
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* either via [method@Gio.Initable.init] or [method@Gio.AsyncInitable.init_async]
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* (the latter is only available if it also implements [iface@Gio.AsyncInitable]).
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*
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* If the object is not initialized, or initialization returns with an
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* error, then all operations on the object except `g_object_ref()` and
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* `g_object_unref()` are considered to be invalid, and have undefined
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* behaviour. They will often fail with [func@GLib.critical] or
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* [func@GLib.warning], but this must not be relied on.
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*
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* Users of objects implementing this are not intended to use
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* the interface method directly, instead it will be used automatically
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* in various ways. For C applications you generally just call
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* [func@Gio.Initable.new] directly, or indirectly via a `foo_thing_new()` wrapper.
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* This will call [method@Gio.Initable.init] under the cover, returning `NULL`
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* and setting a `GError` on failure (at which point the instance is
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* unreferenced).
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*
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* For bindings in languages where the native constructor supports
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* exceptions the binding could check for objects implementing `GInitable`
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* during normal construction and automatically initialize them, throwing
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* an exception on failure.
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*
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* Since: 2.22
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*/
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typedef GInitableIface GInitableInterface;
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G_DEFINE_INTERFACE (GInitable, g_initable, G_TYPE_OBJECT)
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static void
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g_initable_default_init (GInitableInterface *iface)
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{
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}
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/**
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* g_initable_init:
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* @initable: a #GInitable.
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* @cancellable: optional #GCancellable object, %NULL to ignore.
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* @error: a #GError location to store the error occurring, or %NULL to
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* ignore.
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*
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* Initializes the object implementing the interface.
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*
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* This method is intended for language bindings. If writing in C,
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* g_initable_new() should typically be used instead.
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*
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* The object must be initialized before any real use after initial
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* construction, either with this function or g_async_initable_init_async().
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*
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* Implementations may also support cancellation. If @cancellable is not %NULL,
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* then initialization can be cancelled by triggering the cancellable object
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* from another thread. If the operation was cancelled, the error
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* %G_IO_ERROR_CANCELLED will be returned. If @cancellable is not %NULL and
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* the object doesn't support cancellable initialization the error
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* %G_IO_ERROR_NOT_SUPPORTED will be returned.
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*
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* If the object is not initialized, or initialization returns with an
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* error, then all operations on the object except g_object_ref() and
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* g_object_unref() are considered to be invalid, and have undefined
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* behaviour. See the [introduction][ginitable] for more details.
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*
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* Callers should not assume that a class which implements #GInitable can be
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* initialized multiple times, unless the class explicitly documents itself as
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* supporting this. Generally, a class’ implementation of init() can assume
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* (and assert) that it will only be called once. Previously, this documentation
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* recommended all #GInitable implementations should be idempotent; that
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* recommendation was relaxed in GLib 2.54.
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*
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* If a class explicitly supports being initialized multiple times, it is
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* recommended that the method is idempotent: multiple calls with the same
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* arguments should return the same results. Only the first call initializes
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* the object; further calls return the result of the first call.
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*
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* One reason why a class might need to support idempotent initialization is if
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* it is designed to be used via the singleton pattern, with a
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* #GObjectClass.constructor that sometimes returns an existing instance.
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* In this pattern, a caller would expect to be able to call g_initable_init()
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* on the result of g_object_new(), regardless of whether it is in fact a new
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* instance.
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*
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* Returns: %TRUE if successful. If an error has occurred, this function will
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* return %FALSE and set @error appropriately if present.
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*
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* Since: 2.22
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*/
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gboolean
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g_initable_init (GInitable *initable,
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GCancellable *cancellable,
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GError **error)
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{
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GInitableIface *iface;
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g_return_val_if_fail (G_IS_INITABLE (initable), FALSE);
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iface = G_INITABLE_GET_IFACE (initable);
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return (* iface->init) (initable, cancellable, error);
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}
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/**
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* g_initable_new:
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* @object_type: a #GType supporting #GInitable.
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* @cancellable: optional #GCancellable object, %NULL to ignore.
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* @error: a #GError location to store the error occurring, or %NULL to
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* ignore.
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* @first_property_name: (nullable): the name of the first property, or %NULL if no
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* properties
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* @...: the value if the first property, followed by and other property
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* value pairs, and ended by %NULL.
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*
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* Helper function for constructing #GInitable object. This is
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* similar to g_object_new() but also initializes the object
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* and returns %NULL, setting an error on failure.
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*
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* Returns: (type GObject.Object) (transfer full): a newly allocated
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* #GObject, or %NULL on error
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*
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* Since: 2.22
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*/
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gpointer
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g_initable_new (GType object_type,
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GCancellable *cancellable,
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GError **error,
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const gchar *first_property_name,
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...)
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{
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GObject *object;
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va_list var_args;
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va_start (var_args, first_property_name);
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object = g_initable_new_valist (object_type,
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first_property_name, var_args,
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cancellable, error);
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va_end (var_args);
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return object;
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}
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/**
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* g_initable_newv:
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* @object_type: a #GType supporting #GInitable.
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* @n_parameters: the number of parameters in @parameters
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* @parameters: (array length=n_parameters): the parameters to use to construct the object
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* @cancellable: optional #GCancellable object, %NULL to ignore.
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* @error: a #GError location to store the error occurring, or %NULL to
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* ignore.
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*
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* Helper function for constructing #GInitable object. This is
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* similar to g_object_newv() but also initializes the object
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* and returns %NULL, setting an error on failure.
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*
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* Returns: (type GObject.Object) (transfer full): a newly allocated
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* #GObject, or %NULL on error
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*
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* Since: 2.22
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* Deprecated: 2.54: Use g_object_new_with_properties() and
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* g_initable_init() instead. See #GParameter for more information.
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*/
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G_GNUC_BEGIN_IGNORE_DEPRECATIONS
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gpointer
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g_initable_newv (GType object_type,
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guint n_parameters,
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GParameter *parameters,
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GCancellable *cancellable,
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GError **error)
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{
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GObject *obj;
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g_return_val_if_fail (G_TYPE_IS_INITABLE (object_type), NULL);
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obj = g_object_newv (object_type, n_parameters, parameters);
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if (!g_initable_init (G_INITABLE (obj), cancellable, error))
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{
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g_object_unref (obj);
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return NULL;
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}
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return (gpointer)obj;
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}
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G_GNUC_END_IGNORE_DEPRECATIONS
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/**
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* g_initable_new_valist:
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* @object_type: a #GType supporting #GInitable.
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* @first_property_name: the name of the first property, followed by
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* the value, and other property value pairs, and ended by %NULL.
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* @var_args: The var args list generated from @first_property_name.
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* @cancellable: optional #GCancellable object, %NULL to ignore.
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* @error: a #GError location to store the error occurring, or %NULL to
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* ignore.
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*
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* Helper function for constructing #GInitable object. This is
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* similar to g_object_new_valist() but also initializes the object
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* and returns %NULL, setting an error on failure.
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*
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* Returns: (type GObject.Object) (transfer full): a newly allocated
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* #GObject, or %NULL on error
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*
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* Since: 2.22
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*/
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GObject*
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g_initable_new_valist (GType object_type,
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const gchar *first_property_name,
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va_list var_args,
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GCancellable *cancellable,
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GError **error)
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{
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GObject *obj;
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g_return_val_if_fail (G_TYPE_IS_INITABLE (object_type), NULL);
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obj = g_object_new_valist (object_type,
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first_property_name,
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var_args);
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if (!g_initable_init (G_INITABLE (obj), cancellable, error))
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{
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g_object_unref (obj);
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return NULL;
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}
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return obj;
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}
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