[Python-bugs-list] [ python-Bugs-542226 ] octal escape doc contradiction

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Wed, 10 Apr 2002 16:06:53 -0700


Bugs item #542226, was opened at 2002-04-11 09:06
You can respond by visiting: 
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Category: Regular Expressions
Group: None
Status: Open
Resolution: None
Priority: 5
Submitted By: John Machin (sjmachin)
Assigned to: Fredrik Lundh (effbot)
Summary: octal escape doc contradiction

Initial Comment:
Python version 2.2.1, Library Reference, section 
4.2.1

Following is old, correct 
text:

\number
[snip]
If the first digit of number is 0, or 
number is 3 octal digits long, it will not be interpreted as a group 
match, but as the character with octal value number. 

At the end 
of the section, the following has been appended 
recently:

"""Note that octal escapes are not included. While 
the parser can attempt to determine whether a character is being 
specified by it's ordinal value expressed in octal, doing so yields 
an expression which is relatively difficult to maintain, as the 
same syntax is used to refer to numbered groups. """

The first 
sentence is quite incorrect; remove it.

>>> 
re.sub("\157\157", "\165", "foobar")
'fubar'
>>>

The 
second sentence would even if cleaned up and made correct would 
still be out of place in this manual; remove it.

Also document 
that octal numbers are interpreted modulo \400:

>>> 
re.sub("\557\157", "\165", "foobar")
'fubar'
>>>


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