Ensure Python 3 support

[aliafshar]

Let's not be that guy.

Though our crypto dependencies might make this non-trivial.

[dhermes]

+1

Happy to take the lead on this, e.g. use of six and from __future__ import print_function.

[tseaver]

We need to merge the test coverage stuff first, and then review a bunch of str / unicode stuff.

[tseaver]

Dependency status:

• httplib2[1] claims Py3K compatibility
• oauth2client[2] does not document any supported Python versions; its repository CHANGELOG[3] does not list any Py3k compatibility, and it does not install cleanly into a Py33 virtualenv[9]
• protobuf[4] does not document any supported Python verisions; the changelog for 2.6.0[5] claims "Support for Python 3.", but it doesn't install cleanly into a Py33 virtualenv [10]
• pycrypto[6] claims Py3K compatibility
• pyOpenSSL[7] claims Py3K compatibility for 3.2, 3.3
• pytz[8] claims Py3K compatibility

[1] https://pypi.python.org/pypi/httplib2

[2] https://pypi.python.org/pypi/oauthclient

[3] http://github.com/rca/oauthclient

[4] https://pypi.python.org/pypi/protobuf/2.6.0

[5] http://protobuf.googlecode.com/svn/trunk/CHANGES.txt

[6] https://pypi.python.org/pypi/pycrypto

[7] https://pypi.python.org/pypi/pyOpenSSL

[8] https://pypi.python.org/pypi/pytz

[9] https://gist.github.com/tseaver/aae984fc4720ed29e573

[10] https://gist.github.com/tseaver/0531a23cf6ca58fefcea

[dhermes]

It's also worth mentioning that protobuf currently won't install:

The following work-around is required:

$ # Downgrade to fool protobuf: Requirement.parse('python-dateutil>=1.4,<2').
$ sudo pip install -U python-dateutil==1.5
$ # Install with downgraded python-dateutil.
$ sudo pip install protobuf
$ # Upgrade back to newest version of python-dateutil.
$ sudo pip install -U python-dateutil

UPDATE (on 11/2/2014): This was resolved a few weeks ago.

[dhermes]

UPDATE: oauth2client supports Py3

[tseaver]

I'm working today on a branch which uses modernize to fix up bits in the code which will be problematic under Py3k.

[dhermes]

Awesome! protobuf is our only dep which is not over the line yet? Do we have a tracking bug (like protocolbuffers/protobuf#36) in place?

UPDATE:
protocolbuffers/protobuf#7
protocolbuffers/protobuf#9

[tseaver]

I've done some review on google/protobuf/#66: it appears the maintainers believe that preserving 2.5 compatibility is more important than adding 3.x compatibility cleanly.

If we go ahead with #334, we need to solve the problem of Python3 compatibility for /craigcitro/apitools, and its dependencies too. The most problematic one remaining is google-protorpc -- see #60 there, as well as my modernize-prep-py3k branch. Craig is not sanguine about getting even the smaller changeset to land in the internal repo.