使用单利从来没有如此容易和省心过,支持二段式构造,直接贴代码
#ifndef _SINGLETON_H_ #define _SINGLETON_H_ #include "simple_ptr.h" #include <functional> #if defined(_ENABLE_MULTITHREAD) #include <mutex> #endif namespace purelib { namespace gc { /// CLASS TEMPLATE singleton, support delay init with variadic args template<typename _Ty> class singleton { public: template<typename ..._Args> static _Ty* instance(_Args...args) { if (nullptr == singleton<_Ty>::__single__.get()) { #if defined(_ENABLE_MULTITHREAD) singleton<_Ty>::__mutex__.lock(); #endif if (nullptr == singleton<_Ty>::__single__.get()) { singleton<_Ty>::__single__.reset(new _Ty); delay_init(args...); } #if defined(_ENABLE_MULTITHREAD) singleton<_Ty>::__mutex__.unlock(); #endif } return singleton<_Ty>::__single__.get(); } static void destroy(void) { if (singleton<_Ty>::__single__.get() != nullptr) { singleton<_Ty>::__single__.reset(); } } private: template<typename _Fty, typename...Args> static void delay_init(const _Fty& memf, Args...args) { // init use specific member func with more than 1 args std::mem_fn(memf)(singleton<_Ty>::__single__.get(), args...); } template<typename _Fty, typename Arg> static void delay_init(const _Fty& memf, const Arg& arg) { // init use specific member func with 1 arg std::mem_fun(memf)(singleton<_Ty>::__single__.get(), arg); } template<typename _Fty> static void delay_init(const _Fty& memf) { // init use specific member func no args std::mem_fun(memf)(singleton<_Ty>::__single__.get()); } static void delay_init(void) { // no init } private: static simple_ptr<_Ty> __single__; #if defined(_ENABLE_MULTITHREAD) static std::mutex __mutex__; #endif }; template<typename _Ty> simple_ptr<_Ty> singleton<_Ty>::__single__; #if defined(_ENABLE_MULTITHREAD) template<typename _Ty> std::mutex singleton<_Ty>::__mutex__; #endif }; }; #endif /* * Copyright (c) 2012-2014 by X.D. Guo ALL RIGHTS RESERVED. * Consult your license regarding permissions and restrictions. V3.0:2011 */
原文地址:http://blog.csdn.net/xseekerj/article/details/41597941