[Python-Dev] PEP 550 v4

Ethan Furman ethan at stoneleaf.us
Thu Sep 7 08:50:44 EDT 2017

On 09/07/2017 04:39 AM, Greg Ewing wrote:

> 1) Under "Generators" it says:
>     once set in the generator, the context variable is guaranteed
>     not to change between iterations;
> This suggests that you're not allowed to set() a given
> context variable more than once in a given generator,
> but some of the examples seem to contradict that. So I'm
> not sure what this is trying to say.

I believe I can answer this part: the guarantee is that

- the context variable will not be changed while the yield is in effect -- or,
   said another way, while the generator is suspended;

- the context variable will not be changed by subgenerators

- the context variable /may/ be changed by normal functions/class methods
   (since calling them would be part of the iteration)


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