[boost] Re: [boost.optional && boost.variant] Why can't we allowreferences?

From: David Abrahams (dave_at_[hidden])
Date: 2003-08-28 12:03:50

Jaakko Jarvi <jajarvi_at_[hidden]> writes:

> I've noticed that call_traits doesn't support function references.
> I'm not sure whether it makes sense to store function references in 
> optionals, though, but in any case.
>
> Something like this fails:
>
> typedef void (&afuncref)(int);
> typedef call_traits<afunc>::reference t;
>
> The problem is that the call_traits templates have other typedefs in
> the same class, e.g. const_reference, which gets instantiated as
> well, and it adds the const qualifier to a function type.

Just another reason not to write degenerate "traits BLOB"
metafunctions.  call_traits, if it's useful for anything (which I
sometimes wonder about because I have a hard time figuring out what it
does), should be rewritten as separate individual metafunctions.

-- 
Dave Abrahams
Boost Consulting
www.boost-consulting.com