[issue22721] pprint output for sets and dicts is not stable
Fred L. Drake, Jr. added the comment: Sorry for the delay. pprint_safe_key.patch looks good to me. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue22721 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue22721] pprint output for sets and dicts is not stable
Serhiy Storchaka added the comment: Thank you for your review Fred. -- resolution: - fixed stage: patch review - resolved status: open - closed ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue22721 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue22721] pprint output for sets and dicts is not stable
Roundup Robot added the comment: New changeset c8815035116b by Serhiy Storchaka in branch 'default': Issue #22721: An order of multiline pprint output of set or dict containing https://hg.python.org/cpython/rev/c8815035116b -- nosy: +python-dev ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue22721 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue22721] pprint output for sets and dicts is not stable
Serhiy Storchaka added the comment: Ping. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue22721 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue22721] pprint output for sets and dicts is not stable
Serhiy Storchaka added the comment: Ping. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue22721 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue22721] pprint output for sets and dicts is not stable
Serhiy Storchaka added the comment: My question to Raymond is should we use the operator or special methods __lt__ and __gt__ (this is the difference between alternative patches)? The use of repr instead of id is different issue. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue22721 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue22721] pprint output for sets and dicts is not stable
Raymond Hettinger added the comment:
the primary sort will be on the type of quote used for the repr,
which would be surprising and significantly less useful.
How about: repr(obj).strip('\) ?
Overall, the idea of using repr() in some fashion is appealing because it sorts
on what the user actually sees.
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[issue22721] pprint output for sets and dicts is not stable
Serhiy Storchaka added the comment:
How about: repr(obj).strip('\) ?
String can starts or ends with quotes. And string repr can be a part of the
repr of other type (e.g. short list).
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[issue22721] pprint output for sets and dicts is not stable
Antoine Pitrou added the comment: I think it'd be nice if the solution kept the current order when all keys are orderable (which is a very common case). So IMO repr() should only be used as a fallback when the object comparison fails. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue22721 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue22721] pprint output for sets and dicts is not stable
Changes by Raymond Hettinger raymond.hettin...@gmail.com: -- assignee: - rhettinger versions: -Python 3.4 ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue22721 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue22721] pprint output for sets and dicts is not stable
Changes by Raymond Hettinger raymond.hettin...@gmail.com: -- assignee: rhettinger - fdrake ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue22721 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue22721] pprint output for sets and dicts is not stable
Amaury Forgeot d'Arc added the comment: What if [some flavor of] pprint sorted items not by value, but by their repr() string? It's probably faster than any other algorithm, and guaranteed to produce consistent results. Or use this idea only for ambiguous cases? -- nosy: +amaury.forgeotdarc ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue22721 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue22721] pprint output for sets and dicts is not stable
Fred L. Drake, Jr. added the comment: Sorting by the repr sounds good, but if some dict keys or set members are strings containing single-quotes, the primary sort will be on the type of quote used for the repr, which would be surprising and significantly less useful. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue22721 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue22721] pprint output for sets and dicts is not stable
Serhiy Storchaka added the comment: Hmm... is it important? Not more than sorting pprint output at all. This looks low priority issue to me, but the fix looks pretty easy. Here is a patch. I hope Raymond will make a review, may be I missed some details. -- keywords: +patch stage: - patch review Added file: http://bugs.python.org/file37011/pprint_safe_key.patch ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue22721 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue22721] pprint output for sets and dicts is not stable
Serhiy Storchaka added the comment: And here is alternative patch if the first patch is not correct. It is more complicated and I suppose is less efficient in common case. -- Added file: http://bugs.python.org/file37013/pprint_safe_key_alt.patch ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue22721 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue22721] pprint output for sets and dicts is not stable
New submission from Serhiy Storchaka:
pprint() sorts the content of sets and dicts in order to get stable output
which doesn't depend on iteration order of set or dict, which depend not only
from values of elements, but also from set or dict history.
But in some cases the output is different for equal sets or dicts which differs
only by their history.
import pprint
class A: # string 'A' 'int'
... def __lt__(self, other): return False
... def __gt__(self, other): return self != other
... def __le__(self, other): return self == other
... def __ge__(self, other): return True
... def __eq__(self, other): return self is other
... def __ne__(self, other): return self is not other
... def __hash__(self): return 1 # == hash(1)
...
a = A()
sorted([1, a])
[1, __main__.A object at 0xb700c64c]
sorted([a, 1])
[1, __main__.A object at 0xb700c64c]
# set
pprint.pprint({1, a})
{__main__.A object at 0xb700c64c, 1}
pprint.pprint({a, 1})
{1, __main__.A object at 0xb700c64c}
# dict
pprint.pprint({1: 1, a: 1})
{1: 1, __main__.A object at 0xb700c64c: 1}
pprint.pprint({a: 1, 1: 1})
{__main__.A object at 0xb700c64c: 1, 1: 1}
This is happen because _safe_key's __lt__() calls the __lt__() method of it's
left argument, and doesn't use special methods of it's right argument.
a.__lt__(1) is successful, but (1).__lt__(a) is failed.
I think that instead of `self.obj.__lt__(other.obj)` here should be `self.obj
other.obj`. Or may be call other.obj.__gt__(self.obj) if the result of
self.obj.__lt__(other.obj) is NotImplemented.
_safe_key was introduced in issue3976.
--
components: Library (Lib)
messages: 229943
nosy: fdrake, rhettinger, serhiy.storchaka
priority: normal
severity: normal
status: open
title: pprint output for sets and dicts is not stable
type: behavior
versions: Python 3.4, Python 3.5
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[issue22721] pprint output for sets and dicts is not stable
Antoine Pitrou added the comment: Hmm... is it important? -- nosy: +pitrou ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue22721 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue22721] pprint output for sets and dicts is not stable
Fred L. Drake, Jr. added the comment: Stability in output order from pprint is very useful in doctests (yes, some people write documentation that they test). I think fixing any output stability issues would be very worthwhile. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue22721 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
