1ddb351dbec246cf1fab5ec20d2d5520909041de1Kristian Monsen// Copyright (c) 2011 The Chromium Authors. All rights reserved. 2c7f5f8508d98d5952d42ed7648c2a8f30a4da156Patrick Scott// Use of this source code is governed by a BSD-style license that can be 3c7f5f8508d98d5952d42ed7648c2a8f30a4da156Patrick Scott// found in the LICENSE file. 4c7f5f8508d98d5952d42ed7648c2a8f30a4da156Patrick Scott 5c7f5f8508d98d5952d42ed7648c2a8f30a4da156Patrick Scott// Support for using the Singleton<T> pattern with Objective-C objects. A 6c7f5f8508d98d5952d42ed7648c2a8f30a4da156Patrick Scott// SingletonObjC is the same as a Singleton, except the default traits are 7c7f5f8508d98d5952d42ed7648c2a8f30a4da156Patrick Scott// appropriate for Objective-C objects. A typical Objective-C object of type 8c7f5f8508d98d5952d42ed7648c2a8f30a4da156Patrick Scott// NSExampleType can be maintained as a singleton and accessed with: 9c7f5f8508d98d5952d42ed7648c2a8f30a4da156Patrick Scott// 10c7f5f8508d98d5952d42ed7648c2a8f30a4da156Patrick Scott// NSExampleType* exampleSingleton = SingletonObjC<NSExampleType>::get(); 11c7f5f8508d98d5952d42ed7648c2a8f30a4da156Patrick Scott// 12c7f5f8508d98d5952d42ed7648c2a8f30a4da156Patrick Scott// The first time this is used, it will create exampleSingleton as the result 13c7f5f8508d98d5952d42ed7648c2a8f30a4da156Patrick Scott// of [[NSExampleType alloc] init]. Subsequent calls will return the same 14c7f5f8508d98d5952d42ed7648c2a8f30a4da156Patrick Scott// NSExampleType* object. The object will be released by calling 15c7f5f8508d98d5952d42ed7648c2a8f30a4da156Patrick Scott// -[NSExampleType release] when Singleton's atexit routines run 16c7f5f8508d98d5952d42ed7648c2a8f30a4da156Patrick Scott// (see singleton.h). 17c7f5f8508d98d5952d42ed7648c2a8f30a4da156Patrick Scott// 18c7f5f8508d98d5952d42ed7648c2a8f30a4da156Patrick Scott// For Objective-C objects initialized through means other than the 19c7f5f8508d98d5952d42ed7648c2a8f30a4da156Patrick Scott// no-parameter -init selector, DefaultSingletonObjCTraits may be extended 20c7f5f8508d98d5952d42ed7648c2a8f30a4da156Patrick Scott// as needed: 21c7f5f8508d98d5952d42ed7648c2a8f30a4da156Patrick Scott// 22c7f5f8508d98d5952d42ed7648c2a8f30a4da156Patrick Scott// struct FooSingletonTraits : public DefaultSingletonObjCTraits<Foo> { 23c7f5f8508d98d5952d42ed7648c2a8f30a4da156Patrick Scott// static Foo* New() { 24c7f5f8508d98d5952d42ed7648c2a8f30a4da156Patrick Scott// return [[Foo alloc] initWithName:@"selecty"]; 25c7f5f8508d98d5952d42ed7648c2a8f30a4da156Patrick Scott// } 26c407dc5cd9bdc5668497f21b26b09d988ab439deBen Murdoch// }; 27c7f5f8508d98d5952d42ed7648c2a8f30a4da156Patrick Scott// ... 28c7f5f8508d98d5952d42ed7648c2a8f30a4da156Patrick Scott// Foo* widgetSingleton = SingletonObjC<Foo, FooSingletonTraits>::get(); 29c7f5f8508d98d5952d42ed7648c2a8f30a4da156Patrick Scott 30ddb351dbec246cf1fab5ec20d2d5520909041de1Kristian Monsen#ifndef BASE_MEMORY_SINGLETON_OBJC_H_ 31ddb351dbec246cf1fab5ec20d2d5520909041de1Kristian Monsen#define BASE_MEMORY_SINGLETON_OBJC_H_ 323345a6884c488ff3a535c2c9acdd33d74b37e311Iain Merrick#pragma once 33c7f5f8508d98d5952d42ed7648c2a8f30a4da156Patrick Scott 34c7f5f8508d98d5952d42ed7648c2a8f30a4da156Patrick Scott#import <Foundation/Foundation.h> 35ddb351dbec246cf1fab5ec20d2d5520909041de1Kristian Monsen#include "base/memory/singleton.h" 36c7f5f8508d98d5952d42ed7648c2a8f30a4da156Patrick Scott 37c7f5f8508d98d5952d42ed7648c2a8f30a4da156Patrick Scott// Singleton traits usable to manage traditional Objective-C objects, which 38c7f5f8508d98d5952d42ed7648c2a8f30a4da156Patrick Scott// are instantiated by sending |alloc| and |init| messages, and are deallocated 39c7f5f8508d98d5952d42ed7648c2a8f30a4da156Patrick Scott// in a memory-managed environment when their retain counts drop to 0 by 40c7f5f8508d98d5952d42ed7648c2a8f30a4da156Patrick Scott// sending |release| messages. 41c7f5f8508d98d5952d42ed7648c2a8f30a4da156Patrick Scotttemplate<typename Type> 42c7f5f8508d98d5952d42ed7648c2a8f30a4da156Patrick Scottstruct DefaultSingletonObjCTraits : public DefaultSingletonTraits<Type> { 43c7f5f8508d98d5952d42ed7648c2a8f30a4da156Patrick Scott static Type* New() { 44c7f5f8508d98d5952d42ed7648c2a8f30a4da156Patrick Scott return [[Type alloc] init]; 45c7f5f8508d98d5952d42ed7648c2a8f30a4da156Patrick Scott } 46c7f5f8508d98d5952d42ed7648c2a8f30a4da156Patrick Scott 47c7f5f8508d98d5952d42ed7648c2a8f30a4da156Patrick Scott static void Delete(Type* object) { 48c7f5f8508d98d5952d42ed7648c2a8f30a4da156Patrick Scott [object release]; 49c7f5f8508d98d5952d42ed7648c2a8f30a4da156Patrick Scott } 50c7f5f8508d98d5952d42ed7648c2a8f30a4da156Patrick Scott}; 51c7f5f8508d98d5952d42ed7648c2a8f30a4da156Patrick Scott 52c7f5f8508d98d5952d42ed7648c2a8f30a4da156Patrick Scott// Exactly like Singleton, but without the DefaultSingletonObjCTraits as the 53c7f5f8508d98d5952d42ed7648c2a8f30a4da156Patrick Scott// default trait class. This makes it straightforward for Objective-C++ code 54c7f5f8508d98d5952d42ed7648c2a8f30a4da156Patrick Scott// to hold Objective-C objects as singletons. 55c7f5f8508d98d5952d42ed7648c2a8f30a4da156Patrick Scotttemplate<typename Type, 56c7f5f8508d98d5952d42ed7648c2a8f30a4da156Patrick Scott typename Traits = DefaultSingletonObjCTraits<Type>, 57c7f5f8508d98d5952d42ed7648c2a8f30a4da156Patrick Scott typename DifferentiatingType = Type> 58c7f5f8508d98d5952d42ed7648c2a8f30a4da156Patrick Scottclass SingletonObjC : public Singleton<Type, Traits, DifferentiatingType> { 59c7f5f8508d98d5952d42ed7648c2a8f30a4da156Patrick Scott}; 60c7f5f8508d98d5952d42ed7648c2a8f30a4da156Patrick Scott 61ddb351dbec246cf1fab5ec20d2d5520909041de1Kristian Monsen#endif // BASE_MEMORY_SINGLETON_OBJC_H_ 62