When not to use an RE -- an example

[Chris]

What's wrong with:

    def findrepeat(s):  return len(s) > 1 and not filter(lambda x: x !=
s[0], s)

Chris



"John Machin" <sjmachin at lexicon.net> wrote in message
news:c76ff6fc.0304191459.2adf73a at posting.google.com...
> I needed a check for strings consisting of repeated characters -- like
> when users type "ZZZZZZZ" instead of "UNKNOWN" into a database field.
> After implementing the obvious overlapping-substring comparison, I got
> to thinking how this could be done with REs. The following resulted:
>
> import re
> repeats1 = re.compile(r"^(?:(.)(?=\1))+\1\Z", re.DOTALL).match
> def repeats2(s):
>    return len(s) > 1 and s[1:] == s[:-1]
> for testvalue, expected in zip(
>    ['','x','xx','xxx','xxxxxx','xy','xxy','xyy','\n\n\n','aaa\n'],
>    [0,  0,  1,   1,    1,       0,   0,    0,    1,       0     ]):
>    print repr(testvalue), not not repeats1(testvalue),
> repeats2(testvalue), expected
>
> Pergly/phugly, eh? Note the effort required to ensure the newline
> cases worked.