[Python-Dev] Tricky way of of creating a generator via a comprehension expression (original) (raw)

Ivan Levkivskyi levkivskyi at gmail.com
Thu Nov 23 02:38:07 EST 2017

On 23 November 2017 at 05:44, Greg Ewing <greg.ewing at canterbury.ac.nz> wrote:

Ivan Levkivskyi wrote:

The key idea is that neither comprehensions nor generator expressions should create a function scope surrounding the expr

I don't see how you can avoid an implicit function scope in the case of a generator expression, though. And I can't see how to make yield in a generator expression do anything sensible. Consider this: def g(): return ((yield i) for i in range(10)) Presumably the yield should turn g into a generator, but... then what? My brain is hurting trying to figure out what it should do. I think this code should be just equivalent to this code

def g():
    temp = [(yield i) for i in range(10)]
    return (v for v in temp)

Semantics of the comprehension should be clear here (just an equivalent for-loop without name leaking)

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