[Python-Dev] Running Py2.6 with the -3 option

Brett Cannon brett at python.org
Fri Jul 11 22:16:30 CEST 2008

On Fri, Jul 11, 2008 at 12:26 PM, Adam Olsen <rhamph at gmail.com> wrote:
> On Fri, Jul 11, 2008 at 7:02 AM, Steve Holden <steve at holdenweb.com> wrote:
>> Benjamin Peterson wrote:
>>> On Fri, Jul 11, 2008 at 6:24 AM, Raymond Hettinger <python at rcn.com> wrote:
>>>> Some effort needs to be made to clear the standard library of -3
>>>> warnings.
>>>>  Running -3 on production code usually involves exercising library code
>>>> so
>>>> the useful result is obscured by Python complaining about itself.  Since
>>>> that use case involves the users own tests, I don't think the effort
>>>> needs
>>>> to be extended to our own unittest suite.  But the rest of the library
>>>> could
>>>> likely benefit from a good -3 cleanup.
>>> Yes, indeed. We should make sure, however, that the changes in the 2.6
>>> libraries are the absolute minimum to get the job done. (I'm trying to
>>> pretend like this isn't violating the prohibition on all-inclusive
>>> overhauls in the stdlib.)
>> The prohibition is on *gratuitous* changes, basically along the lines of "if
>> it ain't broke, don't fix it". The stdlib is definitely broken if it raises
>> warnings of that kind.
> Is the stdlib broken or is it the warnings that are broken?

Nothing is broken, per se, but the stdlib emits a ton of warnings
through basic usage for Py3K-related changes. We are telling people to
run their code in 2.6 with -3 and to eliminate all warnings in order
to have 2to3 work to transition to 3.0. Having the stdlib itself emit
warnings is just not reasonable.

>  The code
> is just fine in 2.6.  Adding pragmas to disable warnings would be just
> fine.  Or we could hardcode some warnings as "already seen".

No, we should eat our own dog food and transition the code over. If
anything it will help with code maintenance between 2.x and 3.x.


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