Re: Updated PEP 394 (python and python2 commands)

[Thomas Goirand <zigo@debian.org>]

On 05/17/2018 08:53 PM, Matthias Klose wrote:
> PEP 394 [1] saw an update in April 2018 [2], the diffs at [3].
> 
> The most important change from my point of view is
> 
> -* It is suggested that even distribution-specific packages follow the
> -  ``python2``/``python3`` convention, even in code that is not intended to
> +* It is strongly encouraged that distribution-specific packages use ``python2``
> +  or ``python3`` rather than ``python``, even in code that is not intended to
>    operate on other distributions.
> 
> I don't think there is enough time to replace all python shebangs to python2 in
> time for the buster release, however there is no harm in starting this process
> now.  But I'd like to get this done for buster+1, in the case we still need to
> ship a Python2/2.7, so that buster+1 doesn't ship with a python command, but
> maybe with a python2 command.
> 
> The first step is to create a set of python2* packages in python-defaults, with
> contain all the python2* symlinks, and having the python* packages depend on
> those python2 packages.  This change itself is a no-op and shouldn't affect
> anything.
> 
> As a second step change the dh_python2 (in python-defaults), and dh-python to
> generate dependencies on python2 instead of python, and replacing the shebang
> from python to python2.
> 
> This should cover the majority of packages to replace dependencies on python
> with dependencies on python2.  There are packages which don't check for python2,
> so these probably need adjustments.  But again, the goal for buster+1 is to ship
> as few Python2 dependent packages as possible, if any.
> 
> The third step for buster+1 would be to drop the set of python* packages from
> python-defaults.
> 
> Both Debian 8 and Debian 9 already have the python2 symlink, so you could even
> reuse binary packages in the older releases.  If needed, python-defaults could
> be packported to Debian 9 using versioned provides, and to Debian 8 introducing
> the same set of python2 packages.
> 
> Matthias

Hi Matthias,

We need to clear-out something.

Is your proposal includes changing:
"Build-Depends: python{,-all,-dev}"

with:
"Build-Depends: python2{,-all,-dev}"

I don't think that's part of your proposal, but it looks like someone
understood this, I'm not sure why.

Cheers,

Thomas Goirand (zigo)