C++泛型编程学习 std::function

void test(int var)
{
    cout << var <<endl;
}
void calltest(function<void (int)> fun)
{
    fun(120)
};
eg:
    calltest(test);
    
    calltest([](int var)->void{
        cout<< "lambda ===" << var << endl;
})




/*=============================================*/
template<typename T, typename ..Args>
class CFObjHandler
{
public:
virtual T invoke(Args...args)const{};

}
template<Typename U, typename T, typename ...Args>
class CFObjHandlerChild : public CFObjHandler<T, Args...>
{
public:
CFObjHandlerChild(U&& var):functor(std::forward<U>(var))
{
}
virtual T invoke(Args...args)const
{
    return functor(std::forward<Args>(args)...)
};
private:
    U functor;
}


template<typename T>
class CallFuncObj;

template<typename T, typename... Args>
class CallFuncObj<T(Args...)>
{
    template<typename U>
    CallFuncObj(U&& acobj)
    {
        hander = new CFObjHandlerChild<U, T, Args...>(std::forward<U>(acobj));
    }
    ~CallFuncObj()
    {
        delete handler;
    }
public:
    T operator()(Args... args) const
    {
        return hander->invoke(std::forward<Args>(args)...);
    }
private:
    CFObjHandler<T, Args...>*hander;
};

void callObjFun(CallFuncObj<void(int)> cobj)
{
    cobj(120);
}