The new regex imlementation is hosted here: https://code.google.com/p/mrab-regex-hg/

The span of m['a_thing'] is m.span('a_thing'), if that helps.

The named groups are listed on the pattern object, which can be accessed via m.re:

>>> m.re
<_regex.Pattern object at 0x0161DE30>
>>> m.re.groupindex
{'another_thing': 3, 'a_thing': 1}

so you can use that to create a reverse dict to go from the index to the name or None. (Perhaps the pattern object should have such a .group_name attribute.)