線程安全的單例模式實現：
class Lock
{
private:
CCriticalSection m_cs;
public:
Lock(CCriticalSection cs) : m_cs(cs)
{
m_cs.Lock();
}
~Lock()
{
m_cs.Unlock();
}
};
class Singleton
{
private:
Singleton();
Singleton(const Singleton &);
Singleton& operator = (const Singleton &);
public:
static Singleton *Instantialize();
static Singleton *pInstance;
static CCriticalSection cs;
};
Singleton* Singleton::pInstance = 0;
Singleton* Singleton::Instantialize()
{
if(pInstance == NULL)
{ //double check
Lock lock(cs); //用lock實現線程安全，用資源管理類，實現異常安全
//使用資源管理類，在拋出異常的時候，資源管理類對象會被析構，析構總是發生的無論是因爲異常拋出還是語句塊結束。
if(pInstance == NULL)
{
pInstance = new Singleton();
}
}
return pInstance;
}
/*class Singleton
{
private: static Singleton* instance; Singleton();
Singleton(const Singleton &s);
Singleton& operator=(const Singleton &s);
public:
static Singleton* GetInstance()
{
static Singleton instance;
return &instance;
}
};*/