The looming Python 3(000) monster

Jeremy Katz katzj at redhat.com
Fri Dec 5 15:28:02 UTC 2008


On Fri, 2008-12-05 at 09:42 -0500, Michael DeHaan wrote:
> We're just now dealing with Python 2.6, but over on the radar is perhaps 
> one of the most incompatible upgrades to the language we've seen in 
> Python 3.  
[snip]
> So, what of plans?

You do realize that this thread has occurred multiple times now? :)  

> Are we looking at also carrying on with packaging 2.N indefinitely when 
> we do decide to carry 3, because as I know it, the code changes to make 
> something Python 3 compatible will be severe and that's a big item for 
> any release, and will probably result in some undiscovered bugs even 
> after the initial ports (if applied).

Carrying multiple versions of python becomes pretty infeasible very
quickly.  It's easy enough to package just python itself, but any
non-trivial user is going to require modules also.  So how do you decide
which modules to bring in, how to handle the fact that they may have
moved on to python 3 only, etc.  It's a big huge mess.

We'll likely stick with 2.x for a while and watch as python3 matures and
fix things up as we can against 2.6+.  Once there seems to be a critical
mass or compelling reason, we'll get to have a flag day.  Yes it will
hurt.  And for those who also develop things for older distros, yes,
they'll probably need to fork off an old-python or whatever branch and
probably only do bugfixes for some of those distros.  But this is no
different from apache 1.x -> 2.x, anyone doing kernel development, or a
number of other cases that have occurred over the years.

Jeremy




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