And within moments, I hit my first Really Big Problem: Jython
Yep, turns out Jython can't parse 'futurized' python code. Especially dislikes the except <exception>, <var> ---> except <exception> as <var> change. Which isn't very helpful, since the 'as' variant is the only syntax supported by Python 3 (that comma-syntax has been removed). This makes porting the python unit tests to python3 a no go. The non-test python stuff, like the bindings and examples, are not run under jython so it's not a problem there. So what to do? Here's a couple of options that I can think of: 1) don't port the tests to python 3. 2) create two copies of the python tests, one 'old' copy for running under jython, and a new copy for running under python2 and 3. Remove the old tests once jython can handle the modern syntax. 3) Stop running jython tests 4) A better idea I haven't thought of yet. I'm pretty much against option 1 - we need to be able to test the bindings under python 3. I'm open to the others, especially #4. Opinions? -K ----- Original Message ----- > From: "Ken Giusti" <[email protected]> > To: [email protected] > Cc: "Dominic Evans" <[email protected]> > Sent: Thursday, April 16, 2015 9:54:35 AM > Subject: [RFC] Strategy for porting Proton to Python 3 > > > Hi all, > > I'm building on the work done by Dominic and Mickael to get all the proton > python bits to work under both python2 and python3. See [1]. > > I think this will entail a lot of little changes to the python sources and > the unit tests. Rather than check in a single huge patch, I'm going to > break it up over several patches. > > The first bunch of patches will simply 'modernize' the existing python code. > Old style syntax that is not forward compatible with python 3 will be > replaced (eg. print "foo" --> print("foo"), etc). I'll use a tool called > 'futurize' which is part of the python future toolset [2], [3]. > > Once all python code is updated, then I'll begin introducing python 3 > specific patches, including the work already done by Dominic and Mickael. > Of course I'll verify that none of these changes will break python 2. > I've got a local CI system that can build/test in both environments. > > From a discussion with Dominic, we agreed that it would be A Good Thing to > use one of the existing Py2 <--> Py3 abstraction libraries. These libraries > provide utilities for writing code that works under both python versions. > I've used 'six' in the past [4] and found it quite helpful - it will > eliminate a lot of the messy conditional code one has to hack in order to > support both languages. > > However, this library is not part of the standard python library. This means > introducing a new dependency. > > Personally, I don't think this is a big deal - use of 'six' is ubiquitous > among python packages. It's available freely via pypi, and though most > distros. > > So that's the Big Question - is everyone comfortable with this additional > dependency? Does anyone have a better alternative? Has anyone ported > other large python codebases - what was your experience? > > thanks, > > -K > > > [1] https://issues.apache.org/jira/browse/PROTON-490 > [2] http://python-future.org/index.html > [3] http://python-future.org/futurize_cheatsheet.html > [4] https://pythonhosted.org/six/ > > -- > -K > -- -K
