Re: [PATCH v3 2/8] git_remote_helpers: fix input when running under Python 3

From: John Keeping <john@keeping.me.uk>
Date: Jan 23, 2013, 19:47 UTC
Message-ID: <20130123194757.GQ7498@serenity.lan>
In-Reply-To: <CAGdFq_jp3BrS0zgDpmiXGduwu_m4E2CCL+X32P-7T=z9Qk-wuQ@mail.gmail.com>

On Wed, Jan 23, 2013 at 11:20:39AM -0800, Sverre Rabbelier wrote:

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> On Sun, Jan 20, 2013 at 5:15 AM, John Keeping <john@keeping.me.uk> wrote:
> > Although 2to3 will fix most issues in Python 2 code to make it run under
> > Python 3, it does not handle the new strict separation between byte
> > strings and unicode strings.  There is one instance in
> > git_remote_helpers where we are caught by this, which is when reading
> > refs from "git for-each-ref".
> >
> > Fix this by operating on the returned string as a byte string rather
> > than a unicode string.  As this method is currently only used internally
> > by the class this does not affect code anywhere else.
> >
> > Note that we cannot use byte strings in the source as the 'b' prefix is
> > not supported before Python 2.7 so in order to maintain compatibility
> > with the maximum range of Python versions we use an explicit call to
> > encode().
> 
> The three patches that deal with .encode() stuff (2, 7, 8) make me a
> bit uncomfortable, as they add some significant complexity to our
> python code. Is this the recommended way to deal with this (similar to
> the other patch where you linked to the python wiki explaining)?

The best I can offer is this:

http://docs.python.org/3/howto/pyporting.html#deal-with-the-bytes-string-dichotomy

Their recommendation is to use the b() function from the six project, but given that we don't need it in too many places I prefer the approach I took here to adding a thirdparty dependency.

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> As one datapoint, it seems that it's actually Python 2.6 that
> introduces the b prefix.
> 
> http://www.python.org/dev/peps/pep-3112/
> 
> When did we last revisit what minimal python version we are ok with requiring?

I was wondering if people would weigh in discussing that in response to [1] but no one has commented on that part of it. As another datapoint, Brandon Casey was suggesting patching git-p4.py to support Python 2.4 [2].

[1] http://article.gmane.org/gmane.comp.version-control.git/213920 [2] http://article.gmane.org/gmane.comp.version-control.git/214048

John