Forgive my excitement, especially if you are already aware of this, but
this seems like the kind of feature that is easily overlooked (yet could
be very useful):
Both 8-bit and Unicode strings have new partition(sep) and
rpartition(sep) methods that simplify a common use case.
The find(S) method is often used to get an index which is then used to
slice the string and obtain the pieces that are before and after the
separator. partition(sep) condenses this pattern into a single method
call that returns a 3-tuple containing the substring before the
separator, the separator itself, and the substring after the separator.
If the separator isn't found, the first element of the tuple is the
entire string and the other two elements are empty. rpartition(sep) also
returns a 3-tuple but starts searching from the end of the string; the
"r" stands for 'reverse'.
Some examples:
>>> ('http://www.python.org').partition('://')
('http', '://', 'www.python.org')
>>> ('file:/usr/share/doc/index.html').partition('://')
('file:/usr/share/doc/index.html', '', '')
>>> (u'Subject: a quick question').partition(':')
(u'Subject', u':', u' a quick question')
>>> 'www.python.org'.rpartition('.')
('www.python', '.', 'org')
>>> 'www.python.org'.rpartition(':')
('', '', 'www.python.org')
(Implemented by Fredrik Lundh following a suggestion by Raymond Hettinger.)
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