单件模式-Singleton

基于模版的Singleton模式

template<typename T>
class SingleTemp
{
public:
static T* GetInstance()
{
//static T* pInstance = new T(); 其实静态的局部变量,还能简化代码
if (NULL == m_pSingle)
{
m_pSingle = new T();
}
return m_pSingle;
}
protected:
SingleTemp()
{
cout<<"Call SingleTemp()"<<endl;
}
private:
static T* m_pSingle;
};
template<typename T>
T* SingleTemp<T>::m_pSingle = NULL;

class MySingle : public SingleTemp<MySingle>
{
template<typename T>
friend class SingleTemp;
/* 或者
friend class SingleTemp<MySingle>;
*/
private:
MySingle()
{
cout<<"Call MySingle()"<<endl;
}
};