question of style
Sun Jul 5 15:12:25 CEST 2009
Steven D'Aprano <steve at REMOVE-THIS-cybersource.com.au> writes:
> > I wouldn't say Python's None is terrible,...
> No, wait, I tell I lie... re.search() sometimes bites me, because
> sometimes it returns None and sometimes it returns a matchobject and I
> don't use re often enough to have good habits with it yet.
re is a common source of this type of bug but there are others.
> There are three natural approaches to (say) re.search() for dealing with
> (1) return a sentinel value like None;
> (2) return a matchobject which tests False;
> (3) raise an exception.
4. Have re.search return a bool and possible matchobject separately:
put_match_here = 
if re.search(pat, s, target=put_match_here):
or alternatively (cleaner), have a new type of object which supports
search operations while self-updating with the match object:
mt = re.match_target()
if mt.search(pat, s):
if mt.search(pat2, s):
This is sort of inspired by what Perl does. I often do something like
this because it makes it cleaner to chain a series of matches.
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