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

Paul Moore p.f.moore at gmail.com
Wed Nov 22 11:43:28 EST 2017


On 22 November 2017 at 16:30, Ivan Levkivskyi <levkivskyi at gmail.com> wrote:

On 22 November 2017 at 17:24, Antoine Pitrou <solipsis at pitrou.net> wrote:

Given a comprehension (e.g. list comprehension) is expected to work nominally as constructor(generator expression) As Yury just explained, these two are not equivalent if there is an await in the comprehension/generator expression.

As Antoine said, people expect them to work the same. If they don't, then that's a subtle change that came in as a result of the new async functionality. It's a shame that this wasn't made clearer at the time

At the moment, I know I tend to treat Python semantics as I always did, but with an implicit proviso, "unless async is involved, when I can't assume any of my intuitions apply". That's not a good situation to be in.

Paul



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