| // Copyright (c) 2008 The Chromium Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| // Support for using the Singleton<T> pattern with Objective-C objects. A |
| // SingletonObjC is the same as a Singleton, except the default traits are |
| // appropriate for Objective-C objects. A typical Objective-C object of type |
| // NSExampleType can be maintained as a singleton and accessed with: |
| // |
| // NSExampleType* exampleSingleton = SingletonObjC<NSExampleType>::get(); |
| // |
| // The first time this is used, it will create exampleSingleton as the result |
| // of [[NSExampleType alloc] init]. Subsequent calls will return the same |
| // NSExampleType* object. The object will be released by calling |
| // -[NSExampleType release] when Singleton's atexit routines run |
| // (see singleton.h). |
| // |
| // For Objective-C objects initialized through means other than the |
| // no-parameter -init selector, DefaultSingletonObjCTraits may be extended |
| // as needed: |
| // |
| // struct FooSingletonTraits : public DefaultSingletonObjCTraits<Foo> { |
| // static Foo* New() { |
| // return [[Foo alloc] initWithName:@"selecty"]; |
| // } |
| // }; |
| // ... |
| // Foo* widgetSingleton = SingletonObjC<Foo, FooSingletonTraits>::get(); |
| |
| #ifndef BASE_SINGLETON_OBJC_H_ |
| #define BASE_SINGLETON_OBJC_H_ |
| #pragma once |
| |
| #import <Foundation/Foundation.h> |
| #include "base/singleton.h" |
| |
| // Singleton traits usable to manage traditional Objective-C objects, which |
| // are instantiated by sending |alloc| and |init| messages, and are deallocated |
| // in a memory-managed environment when their retain counts drop to 0 by |
| // sending |release| messages. |
| template<typename Type> |
| struct DefaultSingletonObjCTraits : public DefaultSingletonTraits<Type> { |
| static Type* New() { |
| return [[Type alloc] init]; |
| } |
| |
| static void Delete(Type* object) { |
| [object release]; |
| } |
| }; |
| |
| // Exactly like Singleton, but without the DefaultSingletonObjCTraits as the |
| // default trait class. This makes it straightforward for Objective-C++ code |
| // to hold Objective-C objects as singletons. |
| template<typename Type, |
| typename Traits = DefaultSingletonObjCTraits<Type>, |
| typename DifferentiatingType = Type> |
| class SingletonObjC : public Singleton<Type, Traits, DifferentiatingType> { |
| }; |
| |
| #endif // BASE_SINGLETON_OBJC_H_ |