/core/externals/update-engine/externals/google-toolbox-for-mac/Foundation/GTMObjectSingleton.h

 1//
 2//  GTMObjectSingleton.h
 3//  Macro to implement a creation method for a singleton
 4//
 5//  Copyright 2005-2008 Google Inc.
 6//
 7//  Licensed under the Apache License, Version 2.0 (the "License"); you may not
 8//  use this file except in compliance with the License.  You may obtain a copy
 9//  of the License at
10//
11//  http://www.apache.org/licenses/LICENSE-2.0
12//
13//  Unless required by applicable law or agreed to in writing, software
14//  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
15//  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
16//  License for the specific language governing permissions and limitations under
17//  the License.
18//
19
20//
21// This file has been kept around for compatibility with apps relying on its macro,
22// but given how simple this is, there is not a compelling reason for any app to
23// use this macro.
24//
25//  For a reasonable discussion of Objective-C singletons, see
26//  http://eschatologist.net/blog/?p=178
27//
28// Sample usage:
29//
30// GTMOBJECT_SINGLETON_BOILERPLATE(SomeUsefulManager, sharedSomeUsefulManager)
31// (with no trailing semicolon)
32//
33
34#include <AvailabilityMacros.h>
35
36#if (defined(__IPHONE_7_0) && (__IPHONE_OS_VERSION_MAX_ALLOWED >= __IPHONE_7_0)) \
37    || (defined(MAC_OS_X_VERSION_10_9) && (MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_X_VERSION_10_9))
38#error "GTMOBJECT_SINGLETON_BOILERPLATE is deprecated; change this in your sources to a class method using dispatch_once."
39#endif
40
41#if NS_BLOCKS_AVAILABLE
42
43#define GTMOBJECT_SINGLETON_BOILERPLATE(_object_name_, _shared_obj_name_) \
44+ (_object_name_ *)_shared_obj_name_ {     \
45  static _object_name_ *obj;               \
46  static dispatch_once_t onceToken;        \
47  dispatch_once(&onceToken, ^{             \
48     obj = [[self alloc] init];            \
49  });                                      \
50  return obj;                              \
51}
52
53#else
54
55#define GTMOBJECT_SINGLETON_BOILERPLATE(_object_name_, _shared_obj_name_) \
56+ (_object_name_ *)_shared_obj_name_ {     \
57  static _object_name_ *obj;               \
58  if (obj == nil) {                        \
59    obj = [[self alloc] init];             \
60  }                                        \
61  return obj;                              \
62}
63
64#endif  // NS_BLOCKS_AVAILABLE