On 2008-05-18 22:24, Brett Cannon wrote:
On Sun, May 18, 2008 at 6:14 AM, Nick Coghlan <[EMAIL PROTECTED]> wrote:
M.-A. Lemburg wrote:
Perhaps I have a misunderstanding of the reasoning behind
doing the renaming in the 2.x branch, but it appears that
the only reason is to get used to the new names. That's a
rather low priority argument in comparison to the breakage
the renaming will cause in the 2.x branch.
I think this is the key point here. The possibility of breaking pickling
compatibility never came up during the PEP 3108 discussions, so wasn't taken
into account in deciding whether or not backporting the name changes was a
good idea.
I think it's pretty clear that the code needs to be moved back into the
modules with the old names for 2.6. The only question is whether or not we
put any effort into making the new stdlib organisation usable in 2.x, or
just rely on 2to3 to fix it (note that the "increasing the common subset"
argument doesn't really apply, since you can catch the import errors in
order to try both names).
Problem with this is it makes forward-porting revisions to 3.0 a PITA.
By keeping the module names consistent between the versions merging a
revision is just a matter of ``svnmerge merge`` with the usual
3.0-specific changes. Reverting the modules back to the old name will
make forward-porting much more difficult as I don't think svn keeps
rename information around (and thus map the old name to the new name
in terms of diffs).
svnmerge is written in Python, so wouldn't it be possible to add
support for maintaining such renaming to that tool ?
I don't think that an administrative problem such as forward-
porting patches to 3.x warrants breakage in the 2.x branch.
After all, the renaming was approached for Python 3.0 and not
2.6 *because* it introduces major breakage.
AFAIR, the discussion on the stdlib-sig also didn't include the
plan to backport such changes to 2.6. Otherwise, we would have
hashed them out there.
Alexandre's idea of teaching pickle the mapping of old names to new
might be the best solution. We could have a flag to pickle that
deactivates the renaming. Otherwise we could bump the pickle version
number so that the new number doesn't do the mapping while the old
versions to the implicit module mapping.
And as Greg and Glpyh have pointed out, this is a problem that might
need to be addressed in the future with some changes to our
serialization method (I have no clue how since I don't deal with
pickle very much).
It is possible to make pickle aware of the module renames, but
that doesn't solve problems with other forms of serialization
or use of the .__module__ attribute in general.
Why can't we just provide a "from __future__ import renamed_modules"
which then provides all the new name to old name mappings in
some form (e.g. module proxies or whatever) and leave the
existing modules in 2.x untouched ?
--
Marc-Andre Lemburg
eGenix.com
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