[XML-SIG] Finding _xmlplus in Python 2.3a2

[John J Lee]

On Mon, 3 Mar 2003, Martijn Faassen wrote:
[somebody wrote, not sure who]
> > The same is true for any other software package. Any change in a
> > package can cause applications to stop working. So if you don't want
> > to risk a breakage, don't upgrade any software.
> >
> > I cannot see how this is relevant to the _xmlplus technique, though.
>
> You don't know you're upgrading 'the software'. Again, developers
> [...]
> This is not true for software packages that don't use this technique,
> i.e. the rest of the core Python library (at least I hope not!). If I use
> urllib2, it's not magically going to be upgraded as soon as I install some
> other library.

Concrete, precisely analogous (to PyXML) example: I actually maintain a
package that adds features to, and fixes bugs in, urllib2.  I fixed a bug
in the redirect behavior of that module.  In theory, if I made my package
clobber urllib2 on installation, old code would work better, because of
the bug fixes. In actual fact, that bug fix would break old code.  Much
worse, nobody would be expecting this to happen, and people would have to
dig into my code and / or docs to understand what had gone wrong and how
to fix it (if they even figured out that it *was* my code that caused the
problem, which is far from certain).  All of this surprises none of us, of
course, so *why* are we discussing the *merit* of Martin's proposal (which
is clear), rather than the *practicality* (which is debatable)??


John