Re: [boost] [mpl] has_function

Subject: Re: [boost] [mpl] has_function
From: vicente.botet (vicente.botet_at_[hidden])
Date: 2010-03-21 11:51:41

Hi,
----- Original Message ----- 
From: "Lorenzo Caminiti" <lorcaminiti_at_[hidden]>
To: <boost_at_[hidden]>
Sent: Sunday, March 21, 2010 2:11 PM
Subject: [boost] [mpl] has_function

> 
> Hello all,
> 
> Is there a way I can check if a class has a given member function
> using metaprogramming?
> 
> What I need is to check at compile-time if a function is overriding a
> virtual function or not. In the example below, z::f is overriding x::f
> but not y::f (which does not exist) and the compiler knows that -- is
> there a way I can extract that information from the compiler?
> 
>    struct has_function<class Base, ... /* other parameters */ > { ...
> /* some implementation */ };
> 
>    struct x {
>        virtual void f() {}
>    };
> 
>    struct y {
>        virtual void g() {}
>    };
> 
>    struct z: x, y {
>        void f() {
>            cout << has_function<x, &z::f>::value << endl; // print 1
>            cout << has_function<y, &z::f>::value << endl; // print 0
>        }
>    };
> 
> (This does not compile -- I do not know how to program it so it
> compiles -- but it should give the idea of what I am looking for.)

maybe you can take a look at
https://svn.boost.org/trac/boost/wiki/LibrariesUnderConstruction#Boost.ConceptTraits

This library was abandoned because Concepts will be part of the language. It contains alot of traits about if a class ddefines a function. I don't know if there is some some traits for virtual functions.

Let us know,
Vicente