[Python-Dev] None as slice params to list.index() and tuple.index() (original) (raw)
Guido van Rossum guido at python.org
Tue Nov 8 09:41:42 CET 2011
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Hm.
I agree with Raymond that this should be treated as a feature request and not "fixed" in 2.7 / 3.2. (However the mention of 'find' in the error message for 'index' is a bug and should be fixed.)
As for the feature request, I think that allowing None in more places is more regular and consistent across interfaces. I note that the slice() object also represents "missing" or "default" values as None, so it is not just a carryover from the old string.py.
So, +1 on the feature for 3.3; -1 on the "fix" in 3.2 or 2.7.
--Guido
On Sun, Nov 6, 2011 at 11:56 AM, Raymond Hettinger <raymond.hettinger at gmail.com> wrote:
On Nov 6, 2011, at 12:49 AM, Petri Lehtinen wrote: Currently, find(), rfind(), index(), rindex(), count(), startswith() and endswith() of str, bytes and bytearray accept None. Should list.index() and tuple.index() accept it, too? The string methods accept None as a historical artifact of being in string.py where optional arguments defaulted to None. That doesn't imply that you should change every other API that accepts a start argument. The list.index() API is ancient and stable. There has been little or no demonstrated need for its start argument to be None. Also, the list API does not exist in isolation. It shows up in strings, the sequence ABC, and every API that aspires to be list-like. Overall, I'm -1 on this change and find it to be gratuitous. We have way to many micro API changes of dubious benefit. Also, the change should not have been applied to Py2.7 and Py3.2. We don't backport API changes. That would just make Jython and IronPython become non-compliant in mid-stream. Raymond
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-- --Guido van Rossum (python.org/~guido)
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