Re: [gentoo-python] Problem with packages losing python2 compatibility

[grozin@gentoo.org]

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On Mon, 10 Dec 2018, Michał Górny wrote:
> Now, IPython is now split upstream into two branches: 5 and 6.  The old
> branch 5 supports py2+py3 which is good.  The new branch 6 supports py3
> only.  This means that any IPython revdep that requires py2 needs to
> force the old branch.
The current version is 7.2 already. The branch 7 is py3 only, of course.

> Unless someone has a better idea, I think a combined b+c approach might
> be the way to go.  That is:
>
> 1. slot IPython as described above.
>
> 2. update py2+py3 revdeps to use proper cond-dep for slotted version.
>
> 3. slowly drop py2 from revdeps whenever possible.
Seems reasonable. I'm eager to try ipython-7.x.

Another similar case is matplotlib. The branch 3 (not yet in our tree) is 
py3 only. Probably, other major projects will become py3-only soon.

For example, I use py3 whenever I can. But I use a few py2-only 
packages, such as dev-util/diffuse (a very nice gui diff/merge tool, based 
on pygtk, the latest release in 2014). I hope py2.7 and simple py2-only 
packages without numerous deps (like diffuse) will live in the tree for a 
long enough time.

Andrey