[Python-bugs-list] [ python-Bugs-605436 ] Inconsistency in re docs

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Bugs item #605436, was opened at 2002-09-06 02:27
You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=105470&aid=605436&group_id=5470

Category: Python Library
Group: None
Status: Open
Resolution: None
Priority: 5
Submitted By: Christopher A. Craig (ccraig)
Assigned to: Nobody/Anonymous (nobody)
Summary: Inconsistency in re docs

Initial Comment:
>From the Library Reference (2.2.1): 
 
\b    Matches the empty string, but only at the
beginning or end of a 
      word. A word is defined as a sequence of
alphanumeric characters, so 
      the end of a word is indicated by whitespace or a
non-alphanumeric 
      character. Inside a character range, \b
represents the backspace 
      character, for compatibility with Python's string
literals. 
 
Now reality: 
 
Python 2.2.1 (#2, Apr 22 2002, 17:53:10)  
[GCC 2.95.4 20011002 (Debian prerelease)] on linux2 
Type "help", "copyright", "credits" or "license" for
more information. 
>>> import re 
>>> t = re.compile(r'\bbag\b') 
>>> t.search('test bag') 
<_sre.SRE_Match object at 0x812aad0> 
>>> t.search('test+bag') 
<_sre.SRE_Match object at 0x815d528> 
>>> t.search('test_bag') 
>>> [ chr(i) for i in xrange(256) if not
t.search('test' + chr(i) + 
'bag') ] 
['0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A',
'B', 'C', 'D', 
'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O',
'P', 'Q', 'R', 
'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', '_', 'a', 'b',
'c', 'd', 'e', 
'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p',
'q', 'r', 's', 
't', 'u', 'v', 'w', 'x', 'y', 'z'] 
>>>  
 
 
So the implementation appears to define a word as a
sequence of 
alphanumeric characters or underscores, which means
either the 
documentation, or the library is wrong.  Now it happens
that this was 
found while a friend of mine and I were looking to get
the exact 
behavior that is implemented, so I'd prefer it if the
documentation 
were updated to meet the implementation <.8 wink>. 


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