Re: [PATCH 0/8] Initial support for Python 3

john@keeping.me.uk wrote on Sat, 12 Jan 2013 19:23 +0000:

I started having a look to see how much work would be needed to make Git
work with Python 3 and the answer is mostly not much.  The exception is
git-p4.py which is hit hard by the distinction between byte strings and
unicode strings, particularly because the Python output mode of p4
targets Python 2.

I don't know if it's worthwhile to actually apply these but here they
are in case anyone's interested.

Having said that, the changes are minimal and involve either wrapping
parentheses around arguments to print or being a bit more explicit about
how we expect byte strings to be decoded to unicode.

With these patches all tests pass with python3 except t98* (git-p4), but
there are a couple of topics in-flight which will affect that
(fc/remote-testgit-feature-done and er/replace-cvsimport).

John Keeping (8):
  git_remote_helpers: Allow building with Python 3
  git_remote_helpers: fix input when running under Python 3
  git_remote_helpers: Force rebuild if python version changes
  git_remote_helpers: Use 2to3 if building with Python 3
  svn-fe: allow svnrdump_sim.py to run with Python 3
  git-remote-testpy: hash bytes explicitly
  git-remote-testpy: don't do unbuffered text I/O
  git-remote-testpy: call print as a function

 contrib/svn-fe/svnrdump_sim.py     |  4 ++--
 git-remote-testpy.py               | 40 +++++++++++++++++++-------------------
 git_remote_helpers/.gitignore      |  1 +
 git_remote_helpers/Makefile        | 10 ++++++++--
 git_remote_helpers/git/importer.py |  2 +-
 git_remote_helpers/setup.py        | 10 ++++++++++
 6 files changed, 42 insertions(+), 25 deletions(-)

These look good, in that there are relatively few changed needed.

Sebastian Morr tried a similar patch a year ago, in

    http://thread.gmane.org/gmane.comp.version-control.git/187545

He made changes beyond yours, in particular "print >>" lines,
that you seem to handle with 2to3 during the build.  I'm not sure
which approach is better in the long run.  He worked on the
other .py in contrib/ too.

Can you give me some hints about the byte/unicode string issues
in git-p4.py?  There's really only one place that does:

    p4 = subprocess.Popen("p4 -G ...")
    marshal.load(p4.stdout)

If that's the only issue, this might not be too paniful.

I hesitated to take Sebastian's changes due to the huge number of
print() lines, but maybe a 2to3 approach would make that aspect
of python3 support not too onerous.

		-- Pete