[Python-Dev] PEP 550 v4 (original) (raw)

Yury Selivanov yselivanov.ml at gmail.com
Wed Sep 6 19:53:06 EDT 2017

On Wed, Sep 6, 2017 at 1:39 PM, Koos Zevenhoven <k7hoven at gmail.com> wrote: [..]

Now this was of course a completely fictional example, and hopefully I didn't introduce any bugs or syntax errors other than the ones I described. I haven't seen code like this anywhere, but somehow we caught the problems anyway.

Thank you for the example, Koos. FWIW I agree it is a "completely fictional example".

There are two ways how we can easily adapt PEP 550 to follow your semantics:

  1. Set gen.logical_context to None when it is being 'yield frommmed'

  2. Merge gen.logical_context with the outer LC when the generator is iterated to the end.

But I still really dislike the examples you and Greg show to us. They are not typical or real-world examples, they are showcases of ways to abuse contexts.

I still think that giving Python programmers one strong rule: "context mutation is always isolated in generators" makes it easier to reason about the EC and write maintainable code.

Yury

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