[Python-Dev] PEP 3003 - Python Language Moratorium

[Guido van Rossum]

On Thu, Nov 5, 2009 at 3:21 PM, Jesse Noller <jnoller at gmail.com> wrote:
> On Thu, Nov 5, 2009 at 5:53 PM, Dirkjan Ochtman <dirkjan at ochtman.nl> wrote:
>> On Thu, Nov 5, 2009 at 23:05, Guido van Rossum <guido at python.org> wrote:
>>> I haven't seen substantial opposition against the PEP -- in fact I
>>> can't recall any, and many people have explicitly posted in support of
>>> it. So unless opposition suddenly appears in the next few days, I'll
>>> move it to the Accepted state next Monday.
>>
>> Let me state first, I think the PEP is great, and I have no objection
>> to its current form.
>>
>> I do have one qualm, where I wonder if the PEP shouldn't be a little
>> stricter. As a gentoo developer and Mercurial maintainer, most of the
>> pain in the recent migration towards 2.6 has not been in language
>> changes, but in the standard library. Unfortunately, it's exempt from
>> the moratorium in the PEP.
>>
>> Which makes me wonder, why are we not adding another moratorium, on
>> deprecations in the standard library? In other words, let's not
>> deprecate things like md5 or sha or the popen family of functions, but
>> keep all of that as it is, for both 2.x and 3.x, so people can direct
>> their energy towards other things (hopefully porting their 2.x
>> codebase to 3.x).
>>
>> The standard library has already been through a lot of evolution in
>> the 2.x to 3.x transition, so one might assume there's not a lot of
>> stuff in the 3.x stdlib that would need deprecation in the short term.
>> And for 2.x, well, I'd certainly hope we don't need to deprecate much
>> more there before it finally gets EOL'ed, so it should be a relatively
>> light maintenance load to bear.
>>
>> Is this just crazy talk?
>>
>> Cheers,
>>
>> Dirkjan
>>
>
> I'm against restricting deprecation warnings within the stdlib as part
> of this. I actually want more things cleaned up and possibly
> deprecated. That being said, a deprecation warning just means we will
> remove it One Day - anything being deprecated will need a PEP and
> follow the long path to actual removal.
>
> So, -1 from me ;)
>
> jesse

Actually, I think Dirkjan has a point. I'm not sure that we need
another moratorium (that's a rather dramatic kind of decision which
should be very rare indeed) but I do agree that deprecations are often
more of a pain than they're worth.

For example, take the deprecation of the md5 and sha modules in Python
2.6. They make it a bit of a pain to write code that *cleanly*
supports Python 2.4 (doesn't have hashlib) through 2.6 (warns when
importing md5 instead of hashlib). You can silence the warning, but
that is in itself not particularly clean, and users really hate having
the warnings.

I have come to the conclusion that there are better ways to
pre-announce that a module is going to disappear instead of
deprecation warnings.

-- 
--Guido van Rossum (python.org/~guido)