True, False, None (was re. Pruss's manifesto)

[John Roth]

"Thomas Bellman" <bellman at lysator.liu.se> wrote in message
news:boop38$c2l$1 at news.island.liu.se...
> Alex Martelli <aleax at aleax.it> wrote:
>
> > True, False and None may well become keywords in the future, because
that
> > might make things "even finer" in some respects.  E.g., right now,
> >     while True:
> >         ...
> > has to look-up 'True' at EACH step just in case the ... code rebinds
> > that name.  This _is_ a bit silly, when there is no real use-case for
> > "letting True be re-bound".  Nothing major, but...:
>
> That's a silly reason to make them keywords.  A much better way
> to achieve the same goal would be to make the optimizer recognize
> that True isn't re-bound within the loop.  Making the optimizer
> better would improve the performance of much more code than just
> 'while True' loops.

Making them keywords isn't exactly correct. There's a movement
to make just about everything in the built-in scope immutable and
not rebindable at any lower scope for performance reasons. The
usual example is the len() built-in function. All this function does is
call the __len__() method on the object; the extra function call
is a complete waste of time, and could be eliminated if the
compiler could depend on len() never being modified or
rebound at any level.

John Roth
>
>
> -- 
> Thomas Bellman,   Lysator Computer Club,   Linköping University,  Sweden
> "You cannot achieve the impossible without   !  bellman @ lysator.liu.se
>  attempting the absurd."                     !  Make Love -- Nicht Wahr!