At 02:26 PM 4/21/2009 +0200, Lennart Regebro wrote:
So why don't I use that for setuptools? Well, because:
c) The setup of setuptools requires setuptools. So to be able to do
the 2to3 conversion in the setup, I need to first convert the source
with 2to3. Yes, catch 22.
What I still don't get is why it can't work in a 2-stage process,
running one setup.py with distutils to do the build_2to3, and then
running a different setup.py to do the tests.
I imagine that, if I were trying to support Python 3, what I would do
first is make a Python 2 setuptools command that ran 2to3 on a
setuptools-based Python 2 project, and generated a new source tree --
with all sdist-targeted content copied over, and all .py files
converted (including setup.py itself)... and then ran whatever extra
commands you gave, running Python 3 on the resulting setup.py, such that:
python2 setup.py 2to3 test
would automatically do the equivalent of
cd build/2to3; python3 setup.py test
after creating a converted distribution in build/2to3. That way, you
could also do things like:
python2 setup.py test 2to3 test
to run the tests in Python 2 before converting and running them in Python 3.
If somebody wants to create this command, perhaps that would be a
good idea. It can of course be implemented as a plugin, so a change
to setuptools itself is not required.
In the simplest case, the command could just derive from sdist and
build an sdist tree in build/2to3 each time, and then run 2to3 in
place. Or it could reuse sdist and unpack the sdist into the build
tree. This would be slower, but easier to code. A more advanced
version could check for changes in SOURCES.txt between the original
and the build/2to3 directory in order to find files to add/remove,
and only run 2to3 on changed .py files.
Something like:
if not os.path.exists(target_sources_txt):
# wipe build tree, build sdist and unpack
target_manifest = load_manifest(target_sources_txt)
for filename in target_manifest:
if filename not in original_manifest:
# delete file
continue
if is_older_or_nonexistent(filename):
# copy or run 2to3
for filename in original_manifest:
if filename not in target_manifest:
# copy or run 2to3
...but with a lot more os.path.join operations and a lot less
handwaving. ;-) And the initial version of this could just always
do the wipe-and-unpack step, although it'd still need to loop over
the files to run 2to3 anyway, I suppose.
Anyway, I know this is a fair amount of work; It just seems to me
that it has more uses than converting setuptools; i.e., it'd be a
useful rig for anybody doing 2-to-3 porting work.
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