GOTCHA with list comprehension

Chris Angelico rosuav at
Thu Aug 6 06:44:15 CEST 2015

On Thu, Aug 6, 2015 at 2:39 PM, Laura Creighton <lac at> wrote:
> In a message of Wed, 05 Aug 2015 17:05:49 +1000, Chris Angelico writes:
>>Incidentally, why Python 2.6? Python 2.7 has been out for a pretty
>>long time now, and if you can't move to version 3.x, I would at least
>>recommend using 2.7. Since the release of 2.6.9 back before Frozen
>>came out, that branch has been completely unmaintained. Grab yourself
>>a 2.7 and take advantage of some neat new features (for old values of
>>"new"), and improved compatibility with 3.x.
> Be careful suggesting that people upgrade, at least until you have
> found out that they aren't running CentOS enterprise edition. The
> CentOS packaging system is utterly dependent on having the Python
> version it expects, and if you install a more recent version
> (from source, say) the whole packaging system will stop working.
> Recovering from this problem is also very, very difficult  (unless
> you just restore from a recent full backup).
> Been there, done that. :(

Yeah. Fortunately there are ways to leave the system Python untouched
while adding in another Python for some other purpose... and, if
you're desperate enough, you can even leave the Apache-Python bridge
using an older build of Python while running key parts of your web
application in a newer version,  but that requires a certain measure
of insanity!

There will come a time, though, when every supported Linux distro is
shipping either 2.7 or 3.x. And it isn't far off. When that happens,
advising the upgrade will be simple.


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