[Python-Dev] notes from "2 to 3 porting" session of Python Language Summit at PyCon

Trent Mick trentm at activestate.com
Thu Mar 26 23:37:54 CET 2009

My notes from the "2 to 3 porting" session of Python Language Summit at 
PyCon. There were some agreements in this session that people wanted 
recorded. Happy to provide clarification in my notes aren't clear.

## python 2 to 3 migration

- 2to3 distutils flag (part of install or sdist)
- 2to3 is slow: lots of room for speedup (esp. on the matching)
- 3to2
   - good, wanted, needed: esp. by module authors
   - brett: volunteers? silence. Benjamin? Google SOC. Jesse volunteered to
   - decision: want to look into it
   - Want target compat 2.x (which "x"). Can be done by selecting 
   - some discussion of dict views, etc.
- 2.x branch:
   - decision: 18 to 24 month btwn releases.
   - decision: 2.7 (2.6?) *might* be the end of the 2.x line.
- 3.1:
   - in alpha now
   - a2 during the sprints (Brett channeling Benjamin)
   - MvL still has a couple PEPs he wants to propose
   - Jython: considering targetting 3.2 next, *then* maybe 2.7
   - 3.1 will be the one exception to 18-24 mos.
- on "18-24 mo": start a release date PEP with a feature freeze date 
stake in
   the ground when the prev ver is released
- 3.0: special case, not doing 5 years of security releases...
   - hence 3.1 being released soon
   - linux distro guys are fine with that
- extension docs for porting still missing:
   - brett: Benjamin has a draft
   - PortingToPy3k in the wiki
   - Gerhard: doing it against svn
- the other Python implementations: what ver to target
   - depends on their audiences
   - Jython leaning on the latest 3
   - IronPython doesn't want a moving target
   - skip 3.0 and go for 3.1
- python2 & python3 binaries:
   - make install should do it
   - "python3" for new and forever
   - or "python2" for Python 2.x release? Thomas: bad idea because usage of
     "python2" in the shebang line will only work on newer systems



Trent Mick
trentm at gmail.com
trentm at activestate.com

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