Stefan Behnel wrote: [snip]
For comparison, I now implemented the examples from the page as unit tests, which sadly showed that Python's regexps are incompatible with what EXSLT requires. The Python RE "([a-z])+ " does not match "test " as in EXSLT, only the last "t" is returned for the group by re.findall(). So we can't claim compatibility with EXSLT at this point. -- Note, though, that I never really said it was compatible, it just builds on Python's re module. I still think that's enough for a Python XML library.
If it's not compatible, I think it should be invoked differently than in the EXSLT way. This way someone dropping in an EXSLT stylesheet with regexes doesn't have a half-working stylesheet but a completely and clearly failing stylesheet: lxml doesn't support the regexes. In addition, the path forward to getting the stylesheet working is clear: use the Python-based and deliberately incompatible regex facility instead, and rewrite the regexes.