[boost] Function Type Typedefs in Classes, Etc.

From: Paul Mensonides (pmenso57_at_[hidden])
Date: 2003-01-12 00:46:31

Is this well-formed:

struct X {
    typedef void func_t(int);
    func_t member;
};

void X::member(int) {
    return;
}

What about:

struct X {
    typedef void func_t(int) const;
                          // ^^^^^
    func_t member;
};

void X::member(int) const {
    return;
}

This is the root of my question:

template<class> struct test;

template<class R, class C> struct test<R C::*> {
    typedef R type;
};

struct X { };

test< void (X::*)(int) >::type // what type is this?

Is it a function type, or is it a "member function type"?

The reason I ask is I'm trying to make a 'is_ptr_to_mem_fun' traits class
without massive specialization.  This works on Comeau C++:

template<class T> struct is_ptr_to_mem_fun {
    enum { value = false };
};

template<class R, class C> struct is_ptr_to_mem_fun<R C::*> {
    private:
        template<class U> static char check(U (*)[1]);
        template<class U> static char (& check(...))[2];
    public:
        enum { value = sizeof(check<R>(0)) != 1 };
};

struct X { };

int main() {
    std::cout
        << is_ptr_to_mem_fun< int X::* >::value << ' '
        << is_ptr_to_mem_fun< int (X::*)(void) >::value << &std::endl;
    return 0;
}

???
Paul Mensonides