Re: Python versions (was Re: RHEL 8.0 build)

On 25/11/2018 23:14, Tom Lane wrote:
> Andres Freund <andres(at)anarazel(dot)de> writes:
>> On 2018-11-24 15:49:25 -0500, Tom Lane wrote:
>>> There's been some preliminary discussion about starting to default to
>>> python3, but given this project's inherent conservatism, I don't expect
>>> that to happen for some years yet. In any case, whenever we do pull
>>> that trigger we'd surely do so only in HEAD not released branches, so
>>> buildfarm owners will need to deal with the case for years more.
>
>> Why don't we probe for python2 in addition to python by default? That
>> ought to make RHEL 8 work, without making the switch just yet.
>
> I'm unexcited about that because that *would* be expressing a version
> preference --- and one that's on the wrong side of history.

I think it would be appropriate to probe in the order

python python3 python2

This would satisfy most scenarios that are valid under PEP 394.

> Also, I noticed on a fresh FreeBSD 12.0 installation that what
> I've got is
>
> $ ls /usr/bin/pyth*
> ls: /usr/bin/pyth*: No such file or directory
> $ ls /usr/local/bin/pyth*
> /usr/local/bin/python2.7
> /usr/local/bin/python2.7-config
> /usr/local/bin/python3.6
> /usr/local/bin/python3.6-config
> /usr/local/bin/python3.6m
> /usr/local/bin/python3.6m-config
>
> So there are modern platforms on which "python2" isn't going to make
> it work automatically either.

I don't think this is a setup we need to support. You are probably
suppose to install a meta package that will provide a "python" or
"python3" binary.

--
Peter Eisentraut http://www.2ndQuadrant.com/
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