[ovirt-devel] vdsm: python3 support?

[Francesco Romani]

----- Original Message -----
> From: "Dan Kenigsberg" <danken at redhat.com>
> To: devel at ovirt.org
> Sent: Monday, April 27, 2015 5:42:55 PM
> Subject: vdsm: python3 support?
> 
> Vdsm depends on Python 2, but the developers of Python 2 wants us (and
> everybody else) to move to the slightly-different language of Python 3.
> 
> There is a lot to be fixed for this to happen:
> - depency on libraries with no python3 port:
>   - mom
>   - cpopen
>   - m2crypto
> - use of implicit relative imports, mostly in the storage package
> - use of renamed/moved functions, methods and modules (e.g.
>   dict.iteritems, io.StringIO, itertools.izip)
> - use of contextlib.nested
> - unsafe unicode treatment
> - and probably much more...

python 2 string was a mixture of bytes/unicode, now split on python 3.
We have low-level code (JSONRPC & co) which may want/need to carefully audit.

> Fixing it all would take a long time, and may introduce regressions. We
> must perform it gradually.
> 
> The very first step is to use syntax that is compatible with both
> languages, and make sure we do not regress on that front.
[...]

Strong +1

Can we agree about a flow for us developers which
will help not introducing (or at least minimizing) regressions?

Something like an automated test would be the best option I believe
(a-la make pep8/make pyflakes)

There are a few tools that could help, at least in theory, tox
comes first to mind (https://pypi.python.org/pypi/tox) but adapting
VDSM to work seamlessly with tox can require a large amount of work.

I don't specifically advocate tox -I use and I like it, that's it-
anything else which helps is welcome too.

Bests,

-- 
Francesco Romani
RedHat Engineering Virtualization R & D
Phone: 8261328
IRC: fromani