[Python-Dev] Tricky way of of creating a generator via a comprehension expression

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>

> 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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