[Python-Dev] EuroPython Language Summit report (original) (raw)

Mark Dickinson dickinsm at gmail.com
Fri Jun 24 10:52:40 CEST 2011

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EuroPython 2011 Language Summit

Here's a brief report on the EuroPython 2011 Language Summit, held on Sunday 19 June, 2011 in Florence. It was a fairly small meeting, with a lot of informal and loosely-focused discussion and few conclusions reached. I've outlined the topics that we discussed below.

Present:

Antonio Cuni
Mark Dickinson
Larry Hastings (chair)
Marc-André Lemburg
Ezio Melotti
Antoine Pitrou
Armin Ronacher
Armin Rigo
Mark Ramm

Topics covered

Python 3 adoption

This was a long and wide-ranging discussion on the general state of Python 3 adoption. Some highlights:

• Even amongst those present at the meeting, most are still using Python 2 for everyday work.

• pypy: no definitive plans yet for PyPy supporting Python 3.

• The web community is still very much focused on Python 2.

• There's ongoing work (or perhaps just discussion?) on being able to generate Python 3 documentation using Sphinx running on Python 3. This would be particularly useful when using extensions like 'autodoc' for Python 3 code.

• [Armin Ronacher] Python 3's Unicode support still has some dark areas. One example: when opening a text file for reading and writing, the default encoding used depends on the platform and on various environment variables.

• Regular expression support in Python 3 needs improvement (support for Unicode character classes is a particular need). [Subtopic: what needs to be done to get the new regex module into Python? Should it replace the existing module? What about backwards compatibility issues?]

• 2to3: It's still painful to upgrade a codebase from Python 2 to Python 3, and there doesn't seem to be a consensus on best practices yet.

There was a long discussion that I can't hope to do justice to on whether 2to3 should be part of the standard library or not. (With side discussions on distutils and packaging in Python 3.) Armin Ronacher was one of the main participants in this discussion (and IIUC, the main opponent of having 2to3 in the standard library); Armin, do you want to summarize this?

Another major topic of discussion was on how to manage Python 2 and Python 3 in plugin environments (e.g., Blender): is there some way that both Python 2 and Python 3 plugins could be used within the same system? This got a bit technical; perhaps someone else at the meeting would like to elaborate on this?

State of Python 3 on the web

Brief discussion. Summary: it's improving; better than before. We have CherryPy and WSGI. There are issues in WSGI that are going to become more apparent as more people move to Python 3 frameworks.

Discussion of open PEPS

PEP 3151: (Reworking the OS and IO exception hierarchy.) Antoine summarized this; no real discussion here.

PEP 3118: (Not open, but ...) Revising the buffer protocol. The buffer protocol implementation is still buggy and incomplete. (Mostly okay for 1d buffers, not even close for higher-dimensional work.)

PEP 397: Python launcher for Windows. (This was actually discussed later, after lunch; apologies for messing with the timeline here.) There was some confusion over the purpose of this PEP. Armin Ronacher had some objections to the PEP in its current form, but it's not clear to me what those objects are, or whether they still exist. Armin, care to elaborate?

PEP 0380: Syntax for delegating to a subgenerator.

PEP 3150: Statement local namespaces.

PEP 3152: Cofunctions.

For all three of the above PEPs, there was some feeling that additional syntax changes to the language are unnecessary and make it harder to learn; where possible, we should prefer using 3rd partly libraries.

Issue 12326 (Linux 3)

From the issue report by Charles-François Natali::

Linus recently decided that the next Linux kernel version would 3.0 [1].
As a consequence, sys.platform (which is actually MACHDEP) will be 'linux3'
on machines running Linux 3 kernels, and tests checking explicitely against
'linux2' will either break and won't run.

There was significant discussion on how this should be solved. While there's a lot of discussion already on the tracker, the choice of solution may have significant ramifications, so it seems a good idea that this be discussed more widely on python-dev.

Major questions::

• what should be done with Python 2.7? As it stands, as I understand it, sys.platform will become 'linux3' on Linux 3.x (it's a computed value somewhere) in Python 2.7.2, and since Python 2.7.2 is already out there we can't change that. Some of the proposed solutions to the issue would involve sys.platform changing between Python 2.7.2 and Python 2.7.3; is such a change acceptable for a bugfix release?

• it's easy to fix up all uses of "== 'linux2' " in the standard library; is it okay to just let 3rd party code break here?

• What should be done about Lib/plat-linux2?

The rough consensus at the summit was that for Python 2.7 at least, the only realistic solution seems to be to do nothing except document the problem, and point people to the platform module. I'm not sure if this answers the Lib/plat-linux2 question.

Python 2.7

How long will this be maintained? Original decision was 5 years.

PyPI on EC2

There was some discussion several months ago about the possibility of hosting PyPI on EC2. Is this still something that should be considered? PyPI seems to have been much more problem free in recent times.

virtualenv in Python 3.3?

Apparently there was some discussion at the last PyCon about the possibility of virtualenv going into Python 3.3. As far as I know there's currently no open tracker item or PEP for this. Larry Hastings knows more here.

-- Update from Larry: """I'm supportive of putting it in in 3.3, and I'm sitting with Raymond Hettinger right now and he supports it too. So I think if we get a working implementation it'll go in. It's under heavy discussion in c.l.p-d so I gather it's moving forward. Last I knew it was Carl Meyer pushing it forward, but Vinay Sanjip is the current standard-bearer. I understand Windows support will be a bit tricky; I don't know if they have someone who's going to handle it for them."""

Python website

The Python website is painful to edit right now.

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