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Code Issues Releases Wiki Activity

#4882: document named group behavior a bit better.

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Georg Brandl 2009-03-31 19:06:57 +00:00
parent 7558d57ad2
commit 5206086e0d
1 changed files with 9 additions and 7 deletions
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Doc/library/re.rst
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@ -231,16 +231,18 @@ The special characters are:
``(?P<name>...)``
Similar to regular parentheses, but the substring matched by the group is
accessible via the symbolic group name *name*. Group names must be valid Python
identifiers, and each group name must be defined only once within a regular
expression. A symbolic group is also a numbered group, just as if the group
were not named. So the group named 'id' in the example below can also be
referenced as the numbered group 1.
accessible within the rest of the regular expression via the symbolic group
name *name*. Group names must be valid Python identifiers, and each group
name must be defined only once within a regular expression. A symbolic group
is also a numbered group, just as if the group were not named. So the group
named ``id`` in the example below can also be referenced as the numbered group
``1``.
For example, if the pattern is ``(?P<id>[a-zA-Z_]\w*)``, the group can be
referenced by its name in arguments to methods of match objects, such as
``m.group('id')`` or ``m.end('id')``, and also by name in pattern text (for
example, ``(?P=id)``) and replacement text (such as ``\g<id>``).
``m.group('id')`` or ``m.end('id')``, and also by name in the regular
expression itself (using ``(?P=id)``) and replacement text given to
``.sub()`` (using ``\g<id>``).
``(?P=name)``
Matches whatever text was matched by the earlier group named *name*.