Re: Callbacks Again

From: William Kempf (sirwillard_at_[hidden])
Date: 2000-11-20 14:15:42

--- In boost_at_[hidden], Douglas Gregor <gregod_at_r...> wrote:
> On Mon, 20 Nov 2000 16:51:19 -0000
> "William Kempf" <sirwillard_at_m...> wrote:
> 
> [snip]
> > > > (This is one of the things the really confused people in 
SigC, 
> > there
> > > > are multiple formulations there to cover the bad case 
compilers.  
> > It
> > > > makes for reams of code which just gets skipped on most 
> > compilers.)
> > > 
> > > After uploading the newest version of the callback library 
> > yesterday I was lamenting the ugliness of the resulting code. As 
> > careful as I was, the VC++ hacks have produced almost illegible 
> > source from reasonably simple code. 
> > 
> > It doesn't seem that bad to me (at least at the public interface 
> > level... I've yet to look in the ::detail sub-namespace).  
> > Unfortunately, portable code will often have ugly warts, and this 
is 
> > made worse by non-conforming or buggy compilers.  However, you've 
> > done a good job of hiding the ugliness from the user.
> 
> This will change somewhat, because callback should really inherit 
from a callback_impl which is specialized based on the number of 
parameters (just like function_callback_impl in 
details/callback.hpp). Otherwise, we have extranneous, unusable 
operator() overloads in the main callback class.

The extraneous operator() overloads will never be instantiated and so 
never effect code size.  I don't think there's a good reason for 
deriving callback from callback_impl.

In any event, the ugliness is still hidden.

Bill Kempf