[Python-ideas] Add "while" clauses to generator expressions

[Georg Brandl]

Gerald Britton schrieb:
> Hmmm.  I can't really see what you are saying.  Your example doesn't
> quite get the intention.  The "while" clause in the example would
> translate like this:
> 
>      def gen():
>          for i in range(100):
>              if i <= 50:
>                  yield i
>              else:
>                 break
> 
> Also, I think that for a new python user,
> 
> (n for n in range(100) while n*n < 50)
> 
> is easier to understand and use than:
> 
> (n for n in takewhile(lambda n:n*n < 50, range(100)))
>
> My proposed version is shorter (less chance for typos), has one less
> set of parentheses (always a good thing) and reads naturally.

The other is needlessly complicated, though.

takewhile(lambda n: n*n < 50, range(100))

is just as fine, and only 3 characters longer than the proposed while-exp.

Georg

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