PEP-308 a "simplicity-first" alternative
holger krekel
pyth at devel.trillke.net
Tue Feb 11 23:28:16 EST 2003
Tony Lownds wrote:
> holger krekel <pyth at devel.trillke.net> wrote in message news:<mailman.1044992059.13191.python-list at python.org>...
> >Inspired by "do the simplest thing that can possibly work"
> > i now think that
> >
> > x and y else z
> >
> > might just do it and avoid the need for a new construct.
> > It's a very minor change just for fixing the problem at hand.
> >
>
> For this to be a minor change "else" would have to be a binary
> operator:
no, this wouldn't work because
> x and y else z <=> (x and y) else z
the latter had no meaning. and/else really just cures the
x and y or z
idiom by expressing the intention that you want exactly one of
y or z and *don't* want to depend on the boolean value of y.
> After (x and y) is evaluated, the value is false when either x is
> false, or when x is true and y is false. How is "else" meant to
> distinguish the two falses?
It would raise a Syntax error because you really need to say exactly
... and y else z
where "y" and "z" are expressions.
holger
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