[ python-Bugs-1162912 ] typesseq-mutable lacks note on combined key/cmp usage

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Bugs item #1162912, was opened at 2005-03-14 06:20
Message generated for change (Comment added) made by rhettinger
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Category: Documentation
Group: None
Status: Closed
Resolution: Fixed
Priority: 5
Submitted By: Stefan Behnel (scoder)
Assigned to: Reinhold Birkenfeld (birkenfeld)
Summary: typesseq-mutable lacks note on combined key/cmp usage

Initial Comment:
The documentation about list.sort() and sorted() does
not state how the keyword arguments cmp and key
interact. Aparently, if key is supplied, cmp works on
the result of the key function and no longer on the
item itself. This should be documented.

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>Comment By: Raymond Hettinger (rhettinger)
Date: 2005-07-03 23:13

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Actually, it should NOT be documented because 1) it is an
implementation specific detail and 2) using key and cmp
together is almost always the wrong thing to do.

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Comment By: Reinhold Birkenfeld (birkenfeld)
Date: 2005-07-03 15:22

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Thanks for the report and the patch.

Committed as Doc/lib/libstdtypes.tex r1.183, r1.170.2.12.

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Comment By: Peter van Kampen (pterk)
Date: 2005-07-03 15:00

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I have submittted a doc patch (#1231890)  that adds a note
that reads:

If both key and cmp are supplied the key function is
applied before the cmp function.

(You can check listsort in listobject.c to verify)

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