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

[Ivan Levkivskyi]

On 22 November 2017 at 15:46, Antoine Pitrou <solipsis at pitrou.net> wrote:

> On Wed, 22 Nov 2017 15:15:49 +0100
> Ivan Levkivskyi <levkivskyi at gmail.com> wrote:
> > There are many things that I would reject in code review, but they are
> > still allowed in Python,
> > this is one of the reasons why code reviews exist. Also I am not sure how
> > `yield` in a comprehension
> > is more tricky than `await` in a comprehension.
>
> I am not sure either, but do note that "yield" and "await" are two
> different things with different semantics, so allowing "await" while
> disallowing "yield" wouldn't strike me as inconsistent.
>
> The exact semantics of "yield" inside a comprehension is a common
> source of surprise or bewilderment, and the only actual use I've seen
> of it is to show it off as a "clever trick".  So instead of fixing (and
> perhaps complicating) the implementation to try and make it do the
> supposedly right thing, I am proposing to simply disallow it so that
> we are done with the controversy :-)
>
>
Actually, I am not sure there is really a controversy, I have not yet met a
person who _expects_
`yield` in a comprehension to work as it works now, instead everyone thinks
it is just equivalent to a for-loop.

Anyway, I have some compromise idea, will send it in a separate e-mail.

--
Ivan
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