On Jun 15, 2014, at 4:49 AM, Bernhard Rosenkraenzer wrote:
> On 2014-06-15 02:40, Robert Xu wrote:
>> Hi all,
>> In cooker, we've migrated from python2 to python3; but
>> updates-alternatives doesn't seem to be on /usr/bin/python and so
>> basically a ton of python programs are broken now.
>
> Using update-alternatives on something like /usr/bin/python would be a very
> bad idea because it would essentially leave you with 2 evils ("I set python
> to python3, now application A crashes on startup! I fixed it, now python is
> python2, but now I can't run application B!") and because it would make more
> subtle problems hard to reproduce ("Application C crashes when trying to
> print." - "Works here..." - and in the end it turns out that whether or not
> it crashes depends on which python is being used).
>
> The fix here has to be making sure that python2-only things are either fixed
> (often just running 2to3 on them will do the trick) or invoked with python2
> -- usually by editing the first line of the application ("#!/usr/bin/python"
> -> "#!/usr/bin/python2" or "#!/usr/bin/env python" -> "#!/usr/bin/env
> python2").
> Yes, this is going to be some work. (I've already done this for a few things,
> like abf-console-client).
>
> Nobody said this would be a quick and easy transition.
>
> The mass build will automatically fix a few things by making sure libraries
> that are built with whatever /usr/bin/python is will be built with 3 now. But
> it won't magically add "python2" commands.
>
Instead of having *both* pythons (which is more "2 evils are better than 1"),
OMA
should consider being the first linux distro to complete the transition from
python2 -> python3
and focus on incrementally porting any/all remnant legacy packages to python3.
I realize that my comments are heretical. Enjoy the evilness!
73 de Jeff
