[boost] Re: Functions as Filters (was Program Reuse...)

From: Bob Bell (belvis_at_[hidden])
Date: 2005-01-12 18:05:02

christopher diggins <cdiggins <at> videotron.ca> writes:
> ----- Original Message ----- 
> From: "Jonathan Turkanis" <technews <at> kangaroologic.com>
> > I don't see why this is better than
> >
> >   struct toupper_filter : input_filter {
> >        template<typename Source>
> >        int get(Source& src) { return toupper(boost::io::get(src)); }
> >   };
> >
> > and its cousins.
> 
> Then that pretty much closes the discussion. If you do not see the benefits 
> of the lower complexity, then there really is little more I can do to 
> convince you otherwise.

The first thing that's apparent to me is that the actual difference in
complexity between the ToUpper you wrote and the toupper_filter quoted here is
really quite minor. The second thing that's apparent is that your ToUpper relies
on global variables, whereas toupper_filter relies on function arguments, which
in my mind is a more heavily-weighted concern than the complexity difference. My
question is why you do you think relying on globals is a better approach? Some
of your points have been motivated by the needs of novice C++ programmers; do
you really think it is better to advocate a programming style that relies on
global variables?

Bob