[Python-Dev] PEP 550 v4

[Yury Selivanov]

On Wed, Aug 30, 2017 at 8:19 AM, Koos Zevenhoven <k7hoven at gmail.com> wrote:
> On Wed, Aug 30, 2017 at 2:36 AM, Greg Ewing <greg.ewing at canterbury.ac.nz>
> wrote:
>>
>> Yury Selivanov wrote:
>>>
>>> While we want "yield from" to have semantics close to a function call,
>>
>>
>> That's not what I said! I said that "yield from foo()" should
>> have semantics close to a function call. If you separate the
>> "yield from" from the "foo()", then of course you can get
>> different behaviours.
>>
>> But that's beside the point, because I'm not suggesting
>> that generators should behave differently depending on when
>> or if you use "yield from" on them.
>>
>>> For (1) we want the context change to be isolated.  For (2) you say
>>> that the context change should propagate to the caller.
>>
>>
>> No, I'm saying that the context change should *always*
>> propagate to the caller, unless you do something explicit
>> within the generator to prevent it.
>>
>> I have some ideas on what that something might be, which
>> I'll post later.
>>
>
> FYI, I've been sketching an alternative solution that addresses these kinds
> of things. I've been hesitant to post about it, partly because of the
> PEP550-based workarounds that Nick, Nathaniel, Yury etc. have been
> describing, and partly because that might be a major distraction from other
> useful discussions, especially because I wasn't completely sure yet about
> whether my approach has some fatal flaw compared to PEP 550 ;).

We'll never know until you post it. Go ahead.

Yury