[Python-Dev] PEP 394 - Clarification of what "python" command should invoke

[Bohuslav Kabrda]

----- Original Message -----
> On 30 September 2014 20:13, Bohuslav Kabrda <bkabrda at redhat.com> wrote:
> > ----- Original Message -----
> >> On 20 September 2014 00:23, Donald Stufft <donald at stufft.io> wrote:
> >> >
> >> > On Sep 19, 2014, at 10:16 AM, Barry Warsaw <barry at python.org> wrote:
> >> >
> >> > If the user wants to invoke Python 3, it's not hard to type 'python3'
> >> > and I
> >> > think that's the message we should be spreading.  That already seems
> >> > pretty
> >> > ingrained in user habits afaict.
> >> >
> >> >
> >> > My biggest problem with ``python3``, is what happens after 3.9. I know
> >> > Guido
> >> > doesn’t particularly like two digit version numbers and it’s been
> >> > suggested
> >> > on
> >> > this list that instead of 3.10 we’re likely to move directly into 4.0
> >> > regardless of
> >> > if it’s a “big” change or not.
> >>
> >> FWIW, I think we actually do this better on Windows these days, where
> >> PEP 397 made "py" a switchable entry point. I'd like to bring the same
> >> scheme to POSIX systems at some point, but that's a *long* way down
> >> the todo list (like, so far down I can't even see it any more). I'd be
> >> willing to review proposals, though :)
> >
> > We did a similar thing with Ruby in Fedora, it's called Rubypick [1]. Is
> > that a direction worth pursuing?
> 
> Yes, I think so. The general idea would be to take the PEP 397
> launcher CLI and propose a similar API for *nix systems:
> https://docs.python.org/3/using/windows.html#python-launcher-for-windows

Thanks, I'll try looking into this if I get some free time...

> > Also, what is actually result of this thread? AFAICS the PEP still hasn't
> > changed. IMO when there's only python3 installed, there should be no
> > /usr/bin/python, which also seems to be aligned with what Guido says.
> > Would it be possible to update the PEP accordingly?
> 
> Thanks for the prompt. I just pushed an update [1,2] to merge the
> previously incorrect bullet point with the one following it, so it now
> reads:
> 
> * The more general ``python`` command should be installed whenever
>   any version of Python 2 is installed and should invoke the same version of
>   Python as the ``python2`` command (however, note that some distributions
>   have already chosen to have ``python`` implement the ``python3``
>   command; see the `Rationale`_ and `Migration Notes`_ below).

Exactly what I was looking for, thanks a lot!

> I also pushed a few tweaks to account for the extension of Python 2.7
> maintenance, and to change the verb tense to reflect the fact this was
> implemented ages ago [3].
> 
> Cheers,
> Nick.
> 
> [1] https://hg.python.org/peps/rev/3d16b0cd10bc
> [2] https://hg.python.org/peps/rev/32b6619e9259
> [3] https://hg.python.org/peps/rev/0418f146b50f
> 
> --
> Nick Coghlan   |   ncoghlan at gmail.com   |   Brisbane, Australia
> 

-- 
Regards,
Slavek Kabrda