[petsc-dev] python2 vs python3 wrt configure

[Satish Balay]

On Thu, 24 Oct 2013, Jed Brown wrote:

> Satish Balay <balay at mcs.anl.gov> writes:
> 
> > Do you know if archlinux will switch over to using the guideline from python.org?
> 
> The guideline does not prohibit Arch from doing what they did (3 years
> ago).

Yeah - it appears guideline came up in response to what archlinux did
- and that broke stuff.

It says:

- all distributions should ensure that python refers to the same target as python2.

- but archlinux doesn't do this. So users should use 'python2'

But then - as you said - python 2.4 doesn't provide python2

>  It says that scripts should use "python2" if they will only work
> for python-2.x and use "python" if they work for both python-2.x (x=6 or
> 7 in practice) and 3.y.
> 
> > We are currently using python version from RHEL as a guideline. RHEL5
> > has python 2.4 with eol in march-2017.
> >
> > And I see RHEL6 has python-2.6
> 
> Python-2.5 was released in 2006, so this is more than 10 years.  We're
> not very tolerant of PETSc users that are still using petsc-2.1.2.

This comparision is not fair. Configure is supporsed to be
as-portable-as-reasonably possible.

We don't impose the same thing to petsc [i.e all new versions of petsc
should be backward compatible with old versions]

Satish

> 
> This is not to say we have to drop support right away, but python-2.4 is
> getting quite old and forces us to use a number of more fragile
> constructs.  We may have trouble holding out until 2017.
>