increasing the python requirement

[Andrew Bennetts]

Gordon Tyler wrote:
> On 1/4/2011 6:44 PM, Martin Pool wrote:
> > Any of these seem like a high price to pay if the benefit is just
> > getting to use some nicer python2.5/2.6 source constructs.
> 
> There's also improvements/bugfixes in newer python runtimes/VMs to be
> considered.

I know of some performance improvements in the VM, but we get those
simply by running under CPython 2.6.  No effort (aside from supporting
2.6, which we already do) from us is necessary.

What sort of bug fixes do you have in mind?  There are some bugs in the
standard library that we have to work around, and having one less major
version of the standard library to deal with would ease that burden a
little.  e.g. the recent fix for HTTPS under Python 2.7 would probably
have been easier and cleaner if we didn't need to support 2.4.  I don't
think that is a particularly large cost though.

It's interesting to grep for “python2.4” and “[Pp]ython 2.4” in our
source.  It finds a fair few scattered workarounds for various issues,
but we wouldn't gain much now from deleting them.

The main thing I'm tempted by is context managers, but given that
bzrlib.cleanup provides an adequate alternative that works under 2.4
even that's not so important.

I agree with Martin that these benefits don't seem to outweigh the
enormous costs of backporting significant changes to a 2.4 compatible
version.

-Andrew.