Fn, FnMut, FnOnce hierarchy in C++

gistfile1.cpp

template<typename Return, typename... Arguments>
struct FnOnce
{
    using This = FnOnce<Return, Arguments...>;

    virtual Return operator ()(Arguments&&...) && = 0;
};

template<typename Return, typename... Arguments>
struct FnMut: FnOnce<Return, Arguments...>
{
    using This = FnMut<Return, Arguments...>;

    virtual Return operator ()(Arguments&&...) & = 0;

    Return operator ()(Arguments&&... arguments) && final override
    {
        return ((This&)(*this))(std::forward<Arguments>(arguments)...);
    }
};

template<typename Return, typename... Arguments>
struct Fn: FnMut<Return, Arguments...>
{
    using This = Fn<Return, Arguments...>;

    virtual Return operator ()(Arguments&&...) const & = 0;

    Return operator ()(Arguments&&... arguments) & final override
    {
        return ((This const&)(*this))(std::forward<Arguments>(arguments)...);
    }
};