Python 2 support

[faassen]

Would you accept a Python 2 support PR?

It looks like not a lot of code changes are required.

I played around a little, here are my findings:

• the Cython code just compiles and seems to work on Python 2 unchanged

• the __all__ in the __init__.py fails, because I think __all__ in Cython is a unicode object, something Python 2 doesn't like. I'd advocate changing the __init__.py to explicitly import everything needed instead of doing a from .. import *. This way you are in full control of what's exposed in the public API.

• the test suite relies on some features from Python 3:

  • in particular unitest.mock, which is available as mock on PyPI so that's easy
  • assertRaisesRegex which is missing. It'd need to be backported, or the test rewritten
    as the regexes used aren't complicated.
  • subTest, either backported or the test rewritten.

  I'm a fan of pytest myself so alternatively we can port the tests over over to that; it's compatible
  with Python 2 and Python 3. I'd be happier doing that instead.

• I recommend a tool like tox so we can easily run the tests on both Pythons.

• the Makefile is geared towards Python 3, but doesn't do all that much. I just called the build_ext command myself with Python 2. We could cruftify the makefile to support Python 2. Alternatively we could also just simply document the few standard Python commands needed; tox should care of building stuff and running stuff anyway and that's a simple command.

[1st1]

OK, you can make a PR.

the all in the init.py fails, because I think all in Cython is a unicode object, something Python 2 doesn't like. I'd advocate changing the init.py to explicitly import everything needed instead of doing a from .. import *. This way you are in full control of what's exposed in the public API.

Good.

assertRaisesRegex which is missing. It'd need to be backported, or the test rewritten
as the regexes used aren't complicated.

Ideally, I'd like to see assertRaisesRegex ported. I'll be doing more development in httptools later (proper http protocol implementation etc), and I'm used to assertRaisesRegex.

subTest, either backported or the test rewritten.

We can write a rudimentary version for py2.

I recommend a tool like tox so we can easily run the tests on both Pythons.

OK.

the Makefile is geared towards Python 3, but doesn't do all that much. I just called the build_ext command myself with Python 2.

I'd prefer to keep the Makefile as is. Or, you can add a few more targets with a '2' suffix.

[1st1]

BTW, there is this package: https://github.com/benoitc/http-parser/
It appears it uses the same C parser and supports Python 2.

[1st1]

@faassen Are you working on any PR? Because if not (of if you haven't got too far) I'd like to close this issue. Since there is another similar package for Python 2, I see no point in migrating this one.

[grigi]

assertRaisesRegex is provided by unittest2, and is only needed for Python <= 2.6
Python 2.7 already supports it: https://docs.python.org/2/library/unittest.html#unittest.TestCase.assertRaisesRegexp
It was renamed in Py3.2: https://docs.python.org/3.5/library/unittest.html#unittest.TestCase.assertRaisesRegex
Adding this to the top of the test (or py2 compatibility shim):

try:
    unittest.TestCase.assertRaisesRegex
except AttributeError:
    unittest.TestCase.assertRaisesRegex = unittest.TestCase.assertRaisesRegexp

Will make it just work.

[1st1]

Alright, I'm closing this PR.