[Python-ideas] Pre-conditions and post-conditions

[Paul Moore]

On Thu, 16 Aug 2018 at 10:41, Jonathan Fine <jfine2358 at gmail.com> wrote:
>
> Hi Marko
>
> Thank you for introducing yourself, and clearly stating your question.
> That helps us all. You asked:
>
> > Could somebody update me on the state of the discussion on this matter?
>
> I think bring the existing PEP up to date would be a good starting
> point. Its content hasn't been changed since 2003 (except for PEP-wide
> admin changes. (Recall that Python 3.0 was released in 2008.)
>
> https://www.python.org/dev/peps/pep-0316/
> https://github.com/python/peps/commits/master/pep-0316.txt
>
> In fact, revising the PEP might be enough to answer your question.
> What do you think, Marko?
>
> Experts: is there a process for revising old PEPs, such as this one?
> Or at least a precedent we could follow (or adapt)?

I'm not aware of a formal process, but I'd have thought the following
steps would be a reasonable approach:

1. Review the PEP, and research the discussions that happened at the
time, particularly of interest is why the PEP was deferred.
2. Consider what (if anything) has changed since the original deferral
(which could simply be "time has moved on, people's views may have
changed" but ideally would include a bit more in the way of concrete
motivation).
3. Contact the original PEP author and ask if he is interested in
reopening the discussion, collaborating on a revision, or handing the
PEP over.
4. Start up a discussion here, pointing out the original PEP and
summarising the previous debate and why you want to restart the
discussion. If you're hoping to change the details of the original
PEP, summarise your changes and why you feel they are an improvement
over the original.

To answer the OP's question more directly:

> Could somebody update me on the state of the discussion on this matter?

As far as I am aware, there has been no discussion on this subject
since the PEP 316 discussions which ended up in its deferral. Elazar
mentioned PEP 563, and there *may* have been mention of design by
contract uses in the discussions on that PEP, but you'd have to search
the mailing list archives to confirm that one way or another.

Hence the suggestions that if you want to restart discussion, reviving
PEP 316 is likely the best approach.

Paul