[Python-Dev] PEP 405 (pyvenv) and system Python upgrades

[Nick Coghlan]

On Sat, May 5, 2012 at 6:49 AM, Carl Meyer <carl at oddbird.net> wrote:
> 1) Document it and provide a tool for easily upgrading a venv in this
> situation. This may be adequate. In practice the situation is quite rare:
> 2.6.8/2.7.3 is the only actual example in the history of virtualenv that I'm
> aware of. The disadvantage is that if the problem does occur, the error will
> probably be quite confusing and seemingly unrelated to pyvenv.

I think this is the way to go, for basically the same reasons that we
did it this way this time: there's no good reason to pay an ongoing
cost to further mitigate the risks associated with an already
incredibly rare event.

It would become part of the standard venv debugging toolkit:

Q X.1: Does the problem only occur inside a particular virtual environment?
Q X.2: If yes, did you recently upgrade the system Python to a new
point release?
Q X.3: If yes, did you run <command that updates the Python binary
copy in the virtual environment>?
Q X.4: If no, do so and see if the problem goes away. Even if it still
doesn't work, at least you've eliminated this particular error as a
possible cause.

Personally, I expect that "always update your virtual environment
binaries after updating the system Python to a new point release" will
itself become a recommended practice when using virtual environments.

Cheers,
Nick.

-- 
Nick Coghlan   |   ncoghlan at gmail.com   |   Brisbane, Australia