[PATCH] Use best available python version

[Dafydd Harries]

Ar 30/05/2005 am 17:00, ysgrifennodd Martin Pool:
> On Mon, 2005-05-30 at 16:57 +1000, Michael Ellerman wrote:
> > On Mon, 30 May 2005 16:10, Lalo Martins wrote:
> > > On Mon, 2005-05-30 at 14:09 +1000, Michael Ellerman wrote:
> > > > Hi,
> > > >
> > > > On my Debian box I have Python 2.4, but Python 2.3 is the default.
> > > > Currently bzr settles for Python 2.3, this patch makes it use 2.4 in
> > > > preference if it's there.
> > >
> > > er, why?
> > 
> > Well mainly because I grabbed the latest bzr and it was broken for 2.3.
> > 
> > But generally, it just seems to make sense, the 2.4 compiler might be faster, 
> > have fewer bugs etc. The 2.4 standard libraries presumably have bug fixes and 
> > enhancements too, so why not use them?
> 
> 2.4 is indeed much faster.
> 
> But then why wouldn't a distribution which has both 2.3 and 2.4 make 2.4
> the default?  Perhaps they don't trust 2.4?  I think early debian 2.4
> pythons didn't work well.

The reason is twofold:

 - Each Python release is not 100% compatible with previous releases, so
   changing the default version will likely cause bugs to appear in
   programs which use the default version. (I.e. they refer to
   /usr/bin/python rather than /usr/bin/python2.x.)

 - Most Python packages in Debian have a version for each version of in
   Debian. This is particularly important for those which contain C
   code. It takes time for each package maintainer to add support for a
   new version of Python. Hence, during the transition to a new version,
   there might be (for example) an ElementTree package for Python 2.3
   but not for version 2.4.

The fact that Debian is trying to release at the moment has also slowed
the transition to 2.4 down. Ubuntu, on the other hand, made Python 2.4 a
feature goal for its Hoary release and did the transition for each of
the Python libraries/applications it supports.

What this all adds up to is that "default Python version" != "latest
Python version", so this patch to use the latest if available is, IMHO,
a good idea.

-- 
Dafydd