[Python-Dev] Intention to accept PEP 552 soon (deterministic pyc files)

Guido van Rossum guido at python.org
Sun Oct 1 23:42:18 EDT 2017

On Sun, Oct 1, 2017 at 1:52 PM, Koos Zevenhoven <k7hoven at gmail.com> wrote:

> On Oct 1, 2017 19:26, "Guido van Rossum" <guido at python.org> wrote:
> Your PEP is currently incomplete. If you don't finish it, it is not even a
> contender. But TBH it's not my favorite anyway, so you could also just
> withdraw it.
> I can withdraw it if you ask me to, but I don't want to withdraw it
> without any reason. I haven't changed my mind about the big picture. OTOH,
> PEP 521 is elegant and could be used to implement PEP 555, but 521 is
> almost certainly less performant and has some problems regarding context
> manager wrappers that use composition instead of inheritance.

It is my understanding that PEP 521 (which proposes to add optional
__suspend__ and __resume__ methods to the context manager protocol, to be
called whenever a frame is suspended or resumed inside a `with` block) is
no longer a contender because it would be way too slow. I haven't read it
recently or thought about it, so I don't know what the second issue you
mention is about (though it's presumably about the `yield` in a context
manager implemented using a generator decorated with

So it's really between PEP 550 and PEP 555. And there are currently too
many parts of PEP 555 that are left to the imagination of the reader. So,
again, I ask you to put up or shut up. It's your choice. If you don't want
to do the work completing the PEP you might as well withdraw (once I am
satisfied with Yury's PEP I will just accept it when there's no contender).
If you do complete it I will probably still choose PEP 550 -- but at the
moment the choice would be between something I understand completely and
something that's too poorly specified to be able to reason about it.


> -- Koos
> On Oct 1, 2017 9:13 AM, "Koos Zevenhoven" <k7hoven at gmail.com> wrote:
>> On Sep 29, 2017 18:21, "Guido van Rossum" <guido at python.org> wrote:
>> PS. PEP 550 is still unaccepted, awaiting a new revision from Yury and
>> Elvis.
>> This is getting really off-topic, but I do have updates to add to PEP 555
>> if there is interest in that. IMO, 555 is better and most likely faster
>> than 550, but on the other hand, the issues with PEP 550 are most likely
>> not going to be a problem for me personally.
>> -- Koos

--Guido van Rossum (python.org/~guido)
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.python.org/pipermail/python-dev/attachments/20171001/0172c87a/attachment.html>

More information about the Python-Dev mailing list