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

From: Jaakko Jarvi (jajarvi_at_[hidden])
Date: 2003-08-28 11:18:26

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.

GCC doesn't complain, but e.g. Intel does.

Is it still illegal to form a function type with cv-qualifiers, or was
there a DR about that?

  Jaakko

In our last exciting episode "Joel de Guzman" wrote:

> Joel de Guzman <djowel_at_[hidden]> wrote:
> > Hi again,
> 
> > Take 2:
> 
> >     typedef typename call_traits<T>::param_type
> >     ctor_param;
> 
> >     typedef typename call_traits<typename
> >     remove_reference<T>::type>::param_type assign_param;
> 
> >     typedef typename call_traits<T>::reference
> >     return_type;
> 
> >     optional(typename call_traits<T>::param_type arg);
> >     void reset(assign_param arg);
> >     return_type operator*();

> Whoops! That should be:

>     optional(ctor_param arg);
>     void reset(assign_param arg);
>     return_type operator*();

> Anyway, it's the same.

> -- 
> Joel de Guzman
> http://www.boost-consulting.com
> http://spirit.sf.net

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Best Wishes,
Jaakko Järvi