[Python-Dev] "as" mania
Georg Brandl
g.brandl at gmx.net
Tue Mar 7 18:54:17 CET 2006
Alex Martelli wrote:
> I think the best use cases for 'assignment inside an if or while'
> condition, as far as they go, require `capturing' a SUB-expression of
> the condition, rather than the whole condition. E.g., in C,
>
> while ( (x=next_x()) < threshold ) ...
>
> being able to capture (by `as') only the whole (true or false)
> condition meets a minority of the use cases, so I'm unenthusiastic
> about it.
There are use cases (because every value can be tested for true-ness), such
as the likes of
while file.readline() as line:
BLOCK
(which is not needed for builtin file objects, I know)
or something like
m = re.match(...)
if m.group(1) as filename:
do something with filename
Georg
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