>>> import re
>>> r = re.compile('(a|b*)+')
Traceback (most recent call last):
File "<stdin>", line 1, in ?
File "c:\python24\lib\sre.py", line 180, in compile
return _compile(pattern, flags)
File "c:\python24\lib\sre.py", line 227, in _compile
raise error, v # invalid expression
sre_constants.error: nothing to repeat
but
>>> r = re.compile('(a|b*c*)+')
>>> r.match('def').group()
''
Why is there a difference in behaviour between the two cases. Surely the
two cases are equivalent to:
>>> r = re.compile('(a|b)*')
>>> r.match('def').group()
''
and
>>> r = re.compile('(a|b|c)*')
>>> r.match('def').group()
''
Harvey
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