template用法(c++)

#include <stddef.h>

template<typename T>
class Singleton
{
public:
    static T &getInstance ()
    {
        if(NULL == instance)
        {
            instance = new T();
        }
        return *instance;
    }

    static void delInstance ()
    {
        if(NULL != instance)
        {
            delete instance;
            instance = NULL;
        }
    }

protected:
    Singleton ()
    {
    }
    ~Singleton ()
    {
    }

private:
    Singleton (const Singleton &)
    {
    }
    Singleton &operator = (const Singleton &)
    {
    }
    static T *instance;
};

template<typename T>
T *Singleton<T>::instance = NULL;

/* init*/

class BaseClient{};

class TestClient :public BaseClient, Singleton<MyClass>{};

BaseClient *pClient = NULL;
    switch (id)
    {
        case INDEX1:
            pClient = &TestClient::getInstance();

    break;
    }