[boost] Re: Re: calling bind with literals

From: Dill, John (john-dill_at_[hidden])
Date: 2004-05-07 09:54:35

"Douglas Gregor" <gregod_at_[hidden]> wrote in message news:<200405071039.24725.gregod_at_[hidden]>...
> On Friday 07 May 2004 10:30 am, Dill, John wrote:
> > I see your point.  But, what if instead of argument_traits being pass by
> > value, it by default passes by T const&?  What could be done is to have the
> > bind_t arguments be passed by const reference, and then use
> > reference_wrapper to do type-selection to pass by reference.  It still
> > supports literals, and passes by T const& when it can, but everything that
> > is passed by reference must have a ref( object ).  The compiler would fail
> > if you try to pass a reference without a reference_wrapper because it by
> > default tries to pass a T const&.  This wouldn't require the 2^N overloads
> > but would require you to do a ref( object ) for everything passed by
> > reference.  This might also be a workaround for those compilers that don't
> > support T& and T const& overloading.
> 
> So we'd be trading lvalue support for literal support. In my experience, 
> lvalues are _much_ more important than literals[*], and we've had these 
> semantics for a really long time (they'll be part of the C++ Library TR), so 
> it will take a truly killer argument to change this.
> 
> [*] Thinking of my own work, where I use lots of bind expressions, I remember 
> only once having to name a temporary to get around the T& issue with bind, 
> but can thinking of at least 4 places where I pass lvalues through bind.

Okay, just trying an idea out.  Thanks for your comments.

John