[issue9212] dict_keys purports to implement the Set ABC, but is missing the isdisjoint method
Daniel Stutzbach dan...@stutzbachenterprises.com added the comment: Committed to py3k in r84435. Raymond, do you want to look the commit over before I merge it into 3.1 and 2.7? -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue9212 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue9212] dict_keys purports to implement the Set ABC, but is missing the isdisjoint method
Daniel Stutzbach dan...@stutzbachenterprises.com added the comment: Meant to add: I made some relatively minor changes to Daniel Urban's patch. Mostly, I rearranged the order of a few things to avoid unnecessary work (e.g., only compute len_other if we've already checked that other is a set). Thank you Daniel for the patch! :-) -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue9212 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue9212] dict_keys purports to implement the Set ABC, but is missing the isdisjoint method
Daniel Stutzbach dan...@stutzbachenterprises.com added the comment: Also, credited Daniel Urban for the patch in r84436 (forgot that the first time around -- sorry!). -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue9212 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue9212] dict_keys purports to implement the Set ABC, but is missing the isdisjoint method
Daniel Urban urban.dani...@gmail.com added the comment: Thanks for the corrections. I'm attaching the new patch as issue9212b.diff. I'm using PyAnySet_Check to determine if the other argument is really a set, but I'm not entirely sure, that this is correct. Please let me know if other corrections are needed. -- Added file: http://bugs.python.org/file18702/issue9212b.diff ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue9212 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue9212] dict_keys purports to implement the Set ABC, but is missing the isdisjoint method
Raymond Hettinger rhettin...@users.sourceforge.net added the comment: It would be nice to get this fixed before the next release. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue9212 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue9212] dict_keys purports to implement the Set ABC, but is missing the isdisjoint method
Daniel Stutzbach dan...@stutzbachenterprises.com added the comment: I will aim to spend some time with this (and the similar Issue #9213) today and/or tomorrow, so that it can be committed in time for 3.2a2. -- resolution: - accepted stage: unit test needed - patch review ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue9212 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue9212] dict_keys purports to implement the Set ABC, but is missing the isdisjoint method
Daniel Stutzbach dan...@stutzbachenterprises.com added the comment: Thank you for the patch. We should only iterate over the shorter set if the longer set is really a set and not just a sequence. PySequence_Contains may take O(n) time on a list, making the algorithm an expensive O(n**2) overall. I note that set_isdisjoint doesn't try to examine the lengths. Also, since PyIter_Next returns NULL to indicate the end of the iteration OR to indicate an exception, the end of the function should look like this: Py_DECREF(it); if (PyErr_Occurred()) return NULL; Py_RETURN_TRUE; Other than those two issues, the patch looks good to me. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue9212 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue9212] dict_keys purports to implement the Set ABC, but is missing the isdisjoint method
Daniel Urban urban.dani...@gmail.com added the comment: Unless there is a reason I have missed, I would iterate through the smaller set, which might even be empty or nearly so, rather than either in particular. You're right, here is a new patch. Pseudocode: def isdisjoint(self, other): if self is other: if len(self) == 0: return True else: return False else: if len(other) len(self): self, other = other, self for item in other: if item in self: return False return True -- Added file: http://bugs.python.org/file18172/issue9212a.diff ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue9212 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue9212] dict_keys purports to implement the Set ABC, but is missing the isdisjoint method
Daniel Urban urban.dani...@gmail.com added the comment: The attached patch adds the isdisjoint method to dict_keys and dict_items. Pseudocode for the method: def isdisjoint(self, other): if self is other: if len(self) == 0: return True else: return False else: for item in other: if item in self: return False return True -- keywords: +patch nosy: +durban Added file: http://bugs.python.org/file18158/issue9212.diff ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue9212 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue9212] dict_keys purports to implement the Set ABC, but is missing the isdisjoint method
Terry J. Reedy tjre...@udel.edu added the comment: Titles that fit in the box, like 'Dict.keys lacks .isjoint method.' are easier to read and keep track of. Unless there is a reason I have missed, I would iterate through the smaller set, which might even be empty or nearly so, rather than either in particular. -- nosy: +tjreedy ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue9212 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue9212] dict_keys purports to implement the Set ABC, but is missing the isdisjoint method
Changes by Éric Araujo mer...@netwok.org: -- nosy: +merwok ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue9212 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue9212] dict_keys purports to implement the Set ABC, but is missing the isdisjoint method
Raymond Hettinger rhettin...@users.sourceforge.net added the comment: Concrete classes are allowed to have more features than the corresponding ABC. The ABCs are not intended to be full-featured; instead, they specify the part of the API that will be guaranteed. For example, the union() method for built-in sets allows two or more set arguments, but the corresponding method for the ABC is limited to two arguments. This was an intentional difference, designed to make it easier for people to implement a Set class. That being said, the omission of isdisjoint() was an oversight and I see no reason that this shouldn't be fixed. -- nosy: +rhettinger ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue9212 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue9212] dict_keys purports to implement the Set ABC, but is missing the isdisjoint method
Daniel Stutzbach dan...@stutzbachenterprises.com added the comment:
In this case, the concrete class is the one missing a method.
Concrete classes are allowed to provide more features than the corresponding
ABC, but the converse is not true to the best of my knowledge.
dict_keys .register()s as supporting the Set ABC, so it does not automatically
pick up the method through inheritance. Put another way:
# dict_keys provides the Set ABC API
isinstance({}.keys(), collections.Set)
True
# The Set ABC provides isdisjoint
hasattr(collections.Set, 'isdisjoint')
True
# Ergo, dict_keys should provide isdisjoint ... but it doesn't
hasattr({}.keys(), 'isdisjoint')
False
See also Issue9213 for another case where a concrete class is missing a method
provided by an ABC it claims to support.
I sort of wonder if .register() should verify that the concrete class provides
all of the methods of the ABC.
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[issue9212] dict_keys purports to implement the Set ABC, but is missing the isdisjoint method
Raymond Hettinger rhettin...@users.sourceforge.net added the comment: I had misread you original post. Thought you we saying that the Set ABC was missing disjoint. Disregard my last post. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue9212 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue9212] dict_keys purports to implement the Set ABC, but is missing the isdisjoint method
Changes by Raymond Hettinger rhettin...@users.sourceforge.net: -- priority: normal - high ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue9212 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue9212] dict_keys purports to implement the Set ABC, but is missing the isdisjoint method
New submission from Daniel Stutzbach dan...@stutzbachenterprises.com:
isinstance({}.keys(), collections.Set)
True
[method for method in set(dir(collections.Set)) - set(dir({}.keys()))
... if not method.startswith('_')]
['isdisjoint']
(in Python 2.7, use viewkeys() instead of keys)
dict_items has the same problem.
--
assignee: stutzbach
components: Interpreter Core
messages: 109783
nosy: stutzbach
priority: normal
severity: normal
stage: unit test needed
status: open
title: dict_keys purports to implement the Set ABC, but is missing the
isdisjoint method
versions: Python 2.7, Python 3.1, Python 3.2
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[issue9212] dict_keys purports to implement the Set ABC, but is missing the isdisjoint method
Changes by Daniel Stutzbach dan...@stutzbachenterprises.com: -- type: - behavior ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue9212 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
