function/Function.hpp

template <typename Fun>
class Function;


template <typename Ret, typename... Args>
class Function<Ret(Args...)>
{
private:
    class callable_base
    {
    public:
        virtual Ret call(Args...) = 0;
    };

    template <typename Fun>
    class callable : public callable_base
    {
    private:
        Fun _fun;
    public:
        callable(Fun fun):_fun(fun) {}
        virtual Ret call(Args... args)
        { return _fun(std::forward<Args>(args)...); }
    };

    callable_base* _fun;
public:
    Function() {}

    template <typename Fun>
    Function& operator=(Fun fun)
    {
        _fun = new callable<Fun>(fun);
        return *this;
    }

    Ret operator()(Args... args) const
    { return _fun->call(std::forward<Args>(args)...); }

    ~Function() { delete _fun; }
};