| msg147000 - (view) |
Author: Carl Friedrich Bolz-Tereick (Carl.Friedrich.Bolz) * |
Date: 2011-11-04 09:23 |
| The list.index method does not accept None as start and stop, which makes the error message quite confusing: >>> [1, 2, 3].index(2, None, None) Traceback (most recent call last): File "", line 1, in TypeError: slice indices must be integers or None or have an __index__ method I checked this in 3.2.2 and 2.7.2. Seems similar to #12163. |
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| msg147108 - (view) |
Author: Petri Lehtinen (petri.lehtinen) *  |
Date: 2011-11-05 20:23 |
| The same issue exists for tuples: >>> (1, 2, 3).index(2, None) Traceback (most recent call last): File "", line 1, in TypeError: slice indices must be integers or None or have an __index__ method |
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| msg147111 - (view) |
Author: Roundup Robot (python-dev)  |
Date: 2011-11-05 21:30 |
| New changeset 0f0eda4daac7 by Petri Lehtinen in branch '2.7': Accept None as start and stop parameters for list.index() and tuple.index() http://hg.python.org/cpython/rev/0f0eda4daac7 New changeset 5c1fcaf3cf1c by Petri Lehtinen in branch '3.2': Accept None as start and stop parameters for list.index() and tuple.index() http://hg.python.org/cpython/rev/5c1fcaf3cf1c New changeset c33aa14f4edb by Petri Lehtinen in branch 'default': Accept None as start and stop parameters for list.index() and tuple.index(). http://hg.python.org/cpython/rev/c33aa14f4edb |
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| msg147113 - (view) |
Author: Petri Lehtinen (petri.lehtinen) * |
Date: 2011-11-05 21:32 |
| Committed a fix for both list and tuple. I considered this a bug fix rather than a new feature based on discussion in #11828, especially , and applied the fix to 2.7 and 3.2, too. |
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| msg147114 - (view) |
Author: Raymond Hettinger (rhettinger) * |
Date: 2011-11-05 21:35 |
| The relevant code is in _PyEval_SliceIndex() in Python/ceval.c. |
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| msg147116 - (view) |
Author: Raymond Hettinger (rhettinger) * |
Date: 2011-11-05 21:37 |
| I think this "fix" was too hastily committed. 1) It was an API change. 2) It probably should have been done in _PyEval_SliceIndex(). Be careful. Don't rush to commit. Especially for backports. |
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| msg147117 - (view) |
Author: Petri Lehtinen (petri.lehtinen) * |
Date: 2011-11-05 21:46 |
| > 2) It probably should have been done in _PyEval_SliceIndex(). I saw that other code used the same approach as I used in the fix. The comment above _PyEval_SliceIndex() suggests it's used in other contexts too. It seems that 2.7 uses it to implement the SLICE opcode, while in 3.x it's only used to convert slice-like arguments. What do you suggest? Doing it in _PyEval_SliceIndex() in 2.7 is problematic, as we don't want x[None:2], right? :) |
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| msg147120 - (view) |
Author: Raymond Hettinger (rhettinger) * |
Date: 2011-11-05 22:17 |
| The API in 2.7 shouldn't be changed. The error message can be fixed though. Also, it is not clear that the API should change even in 3.3. The list.index() method is not required to accept None. It is not different than other APIs that use PyArg_ParseTuple() with an "i" field for a start, stop, or step argument. |
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| msg147121 - (view) |
Author: Amaury Forgeot d'Arc (amaury.forgeotdarc) * |
Date: 2011-11-05 22:29 |
| str.index does accept None, though |
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| msg147151 - (view) |
Author: Mark Dickinson (mark.dickinson) * |
Date: 2011-11-06 11:28 |
| > What do you suggest? Doing it in _PyEval_SliceIndex() in 2.7 is > problematic, as we don't want x[None:2], right? :) Eh? Don't we already have this? Python 2.7.2 (default, Aug 22 2011, 13:53:27) [GCC 4.2.1 (Apple Inc. build 5666) (dot 3)] on darwin Type "help", "copyright", "credits" or "license" for more information. >>> range(5)[None:2] [0, 1] Or am I misunderstanding? |
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| msg147153 - (view) |
Author: Petri Lehtinen (petri.lehtinen) * |
Date: 2011-11-06 11:46 |
| > Or am I misunderstanding? Ah, no, sorry. I wasn't aware of this. Now the error message set by _PyEval_SliceIndex() makes sense. It doesn't itself accept None, but apply_slice() and assign_slice() handle the None case. There's still the question whether {list,tuple}.index() should accept None or not. |
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| msg147162 - (view) |
Author: Raymond Hettinger (rhettinger) * |
Date: 2011-11-06 17:13 |
| > There's still the question whether {list,tuple}.index() should accept None or not. The API should not be changed for Py2.7 and Py3.2. Those changesets should be reverted. For Py3.3, it is open to discussion, but we probably don't need the change (making every other implementation also change for nearly zero benefit). |
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| msg147163 - (view) |
Author: Raymond Hettinger (rhettinger) * |
Date: 2011-11-06 17:18 |
| One other thought: the API for list.index() doesn't exist in isolation. There is also str.index, the sequence abstract base class, and tons of code that has been written to emulate lists. This is an ancient API (approx 20 years) and should only be changed with care. IOW, I don't think this change should have been made at all, at least not without a discussion on python-dev and motivating use cases. |
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| msg147171 - (view) |
Author: Roundup Robot (python-dev) |
Date: 2011-11-06 19:15 |
| New changeset 19ffa12ffdd4 by Petri Lehtinen in branch '2.7': Revert "Accept None as start and stop parameters for list.index() and tuple.index()" http://hg.python.org/cpython/rev/19ffa12ffdd4 New changeset ed0e85efac47 by Petri Lehtinen in branch '3.2': Revert "Accept None as start and stop parameters for list.index() and tuple.index()" http://hg.python.org/cpython/rev/ed0e85efac47 New changeset 106f9e1ad7ab by Petri Lehtinen in branch 'default': Revert "Accept None as start and stop parameters for list.index() and tuple.index()" http://hg.python.org/cpython/rev/106f9e1ad7ab |
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| msg147172 - (view) |
Author: Petri Lehtinen (petri.lehtinen) * |
Date: 2011-11-06 19:20 |
| It's now reverted on all branches. I posted to python-dev alreay earlier. |
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| msg228937 - (view) |
Author: R. David Murray (r.david.murray) * |
Date: 2014-10-10 01:22 |
| Per discussion in the issue, I'm changing this to a bugfix on the message text. If the python-dev discussion resulted (or results in the future) in a desire to change the API, that should be a new issue. |
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| msg263582 - (view) |
Author: Berker Peksag (berker.peksag) * |
Date: 2016-04-16 19:36 |
| See http://thread.gmane.org/gmane.comp.python.devel/127502 for the python-dev thread. |
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| msg376958 - (view) |
Author: Irit Katriel (iritkatriel) * |
Date: 2020-09-15 22:09 |
| The error message was fixed under , so I think this issue can now be closed. |
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| msg376977 - (view) |
Author: Serhiy Storchaka (serhiy.storchaka) * |
Date: 2020-09-16 07:15 |
| Thank you for the reminder Irit. Your comments for issues and PRs are really helpful. Thank you for all this! |
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