问模板类方法的专门化

EN

template <typename T>
class MyClass {
private:
    T m_value;

private:
    template<typename U>
    void doSetValue (const U & value) {
        std::cout << "template called" << std::endl;
        m_value = value;
    }

    void doSetValue (float value) {
        std::cout << "float called" << std::endl;
    }

public:
    void SetValue(const T &value) { doSetValue (value); }

};

template <typename T>
class MyClass
{
private:
    T m_value;

public:
    void SetValue(const T &value);

};

template<typename T>
void MyClass<T>::SetValue (const T & value) {
    std::cout << "template called" << std::endl;
    m_value = value;
}

template<>
void MyClass<float>::SetValue (const float & value) {
    std::cout << "float called" << std::endl;
}

template<typename T>
class Helper {
protected:
    T m_value;
    ~Helper () { }

public:
    void SetValue(const T &value) {
        std::cout << "template called" << std::endl;
        m_value = value;
    }
};

template<>
class Helper<float> {
protected:
    float m_value;
    ~Helper () { }

public:
    void SetValue(float value) {
        std::cout << "float called" << std::endl;
    }
};

template <typename T>
class MyClass : public Helper<T> {
};

template <typename T>
class MyClass
{
public:
    template<class U> 
    void SetValue(const U &value) { m_value = value; }
    void SetValue(float value) {do special stuff} 
private:
    T m_value;
};

int main() 
{
     MyClass<int> mc;
     mc.SetValue(3.4); // the template member with U=double will be called
     mc.SetValue(3.4f); // the special function that takes float will be called

     MyClass<float> mcf; //compiles OK. If the SetValue were not a template, 
     // this would result in redefinition (because the two SetValue functions
     // would be the same   
}