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Diffstat (limited to 'Foundation/GTMObjectSingleton.h')
| -rw-r--r-- | Foundation/GTMObjectSingleton.h | 69 |
1 files changed, 69 insertions, 0 deletions
diff --git a/Foundation/GTMObjectSingleton.h b/Foundation/GTMObjectSingleton.h new file mode 100644 index 0000000..ff03ea0 --- /dev/null +++ b/Foundation/GTMObjectSingleton.h @@ -0,0 +1,69 @@ +// +// GTMObjectSingleton.h +// Macro to implement methods for a singleton +// +// Copyright 2005-2008 Google Inc. +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not +// use this file except in compliance with the License. You may obtain a copy +// of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT +// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the +// License for the specific language governing permissions and limitations under +// the License. +// + +/// This macro implements the various methods needed to make a safe singleton. +// +/// This Singleton pattern was taken from: +/// http://developer.apple.com/documentation/Cocoa/Conceptual/CocoaFundamentals/CocoaObjects/chapter_3_section_10.html +/// +/// Sample usage: +/// +/// SINGLETON_BOILERPLATE(GMSomeUsefulManager, sharedSomeUsefulManager) +/// (with no trailing semicolon) +/// +#define GTMOBJECT_SINGLETON_BOILERPLATE(_object_name_, _shared_obj_name_) \ +static _object_name_ *z##_shared_obj_name_ = nil; \ ++ (_object_name_ *)_shared_obj_name_ { \ + @synchronized(self) { \ + if (z##_shared_obj_name_ == nil) { \ + /* Note that 'self' may not be the same as _object_name_ */ \ + /* first assignment done in allocWithZone but we must reassign in case init fails */ \ + z##_shared_obj_name_ = [[self alloc] init]; \ + GTMDebugAssert((z##_shared_obj_name_ != nil), @"didn't catch singleton allocation"); \ + } \ + } \ + return z##_shared_obj_name_; \ +} \ ++ (id)allocWithZone:(NSZone *)zone { \ + @synchronized(self) { \ + if (z##_shared_obj_name_ == nil) { \ + z##_shared_obj_name_ = [super allocWithZone:zone]; \ + return z##_shared_obj_name_; \ + } \ + } \ + \ + /* We can't return the shared instance, because it's been init'd */ \ + GTMDebugAssert(NO, @"use the singleton API, not alloc+init"); \ + return nil; \ +} \ +- (id)retain { \ + return self; \ +} \ +- (unsigned int)retainCount { \ + return UINT_MAX; \ +} \ +- (void)release { \ +} \ +- (id)autorelease { \ + return self; \ +} \ +- (id)copyWithZone:(NSZone *)zone { \ + return self; \ +} \ + |