Is there an error in the way python handles '.' or '\b'? I'm not sure why this produces differing results.
import re
regex1 = r'\.?\b'
print bool(re.match(regex1, '.'))
regex2 = r'a?\b'
print bool(re.match(regex2, 'a'))
Output:
False
True
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2 Answers
\b, word boundary, matches between word characters and non-word elements. As such, it will match between a word character like a and the end of the string, but not between a non-word character like . and end of string.
Comments
As geekosaur pointed out \b is merely a short way of writing
(?:(?<=\w)(?!\w)|(?<!\w)(?=\w))
In your case you may want to use
(?!\w)
or
(?!\S)
instead of \b.
