Re: [boost] Re: Callbacks Again

From: Douglas Gregor (gregod_at_[hidden])
Date: 2000-11-17 18:56:15

On Fri, 17 Nov 2000 15:31:35 -0800
Jesse Jones <jejones_at_[hidden]> wrote:

> >> >> This makes it tougher to include the bool
> >> >>   conversion (how do we know if a functor has a real target or
> >> >>   not?), which I consider essential.
> >> >
> >> >The bool conversion can be handled by inclusion of a default
> >> >constructor that sets the "impl" pointer to null.
> >>
> >> Yep (of course a const void* conversion would be better than bool).
> >
> >Would it?  Didn't we decide the opposite for boost::any?
> 
> Yep. Now that I think about it void*'s aren't quite right here either. If
> all you had were free functions you could return the function address. This
> would still allow you to compare differently typed callbacks, but at least
> you'd get the correct results. However you can't really do this with
> functors...

I don't think that comparison of callbacks should be an issue. The standard
library functors cannot be compared, so unless we are going to extend the
notion of a callback target beyond that of a functor, we shouldn't be 
dealing with comparisons.

        Doug Gregor