Suggestion for a new regular expression extension  Nicolas
LEHUEN nicolas.lehuen at Thu Nov 20 17:15:28 CET 2003   I'm
currently writing various regular expressions designed to help
me parse some real-world French postal addresses. The task is
not easy due to the vast amount of abbreviations, misspelling
and variations in adresses. Just to give you a taste of what the
regular expression looks like (unoptimized and perfectible, but
for now it performs well enough) :  re_adresse = re.compile(r'''
(?P<street_number>\d+(?:[ /\-]\d+)?)?     |   B(?:IS)?     |   C
|   E     |   F     |   T(?:ER|RE)?     |   Q(?:UATER)?     |
B(?:D|LD|VD|OUL(?:EVARD)?)  Note for example the many
abbreviations (correct or not) ouf "boulevard" : BD, BLD, BVD,
BOUL, BOULEVARD. For normalisation purposes, I need to transform
all those forms into the only correct abbreviation, BD.  What
would be really, really neat, would be a regular expression
extension notation that would make the RE engine to return an
arbitrary string when