在平常的开发工作中，单例是我们经常使用的模式，经常我们需要写无数个单例类，现在提供一种单例模板：
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#pragma once// common include#include <stdio.h>#include <stdlib.h>#include <assert.h> // windows include #if defined _WIN32#else// linux include#include <errno.h>#endif template <typename T> class Singleton{protected: static T* singleton_;public: Singleton(void) { assert(!singleton_);#if defined(_MSC_VER) && _MSC_VER < 1200 int offset = (int)(T*)1 - (int)(Singleton <T>*)(T*)1; singleton_ = (T*)((int)this + offset);#else singleton_ = static_cast< T* >(this);#endif } ~Singleton(void){ assert(singleton_); singleton_ = 0; } static T& getSingleton(void) { assert(singleton_); return (*singleton_); } static T* getSingletonPtr(void){ return singleton_; }};#define _SINGLETON_INIT( TYPE ) template <> TYPE * Singleton< TYPE >::singleton_ = 0; |
用法:
class A:public Singleton<A>
{
};
在cpp文件中:
template<> A* Singleton<A>::singleton_ = 0;
_SINGLETON_INIT(A)