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

[Ivan Levkivskyi]

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)

--
Ivan
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