[Python-checkins] Expand the implementation comments (GH-19699) (GH-19701)
Miss Islington (bot)
webhook-mailer at python.org
Fri Apr 24 06:04:46 EDT 2020
https://github.com/python/cpython/commit/c7b55e929b35ccab552f9efd49eed4a168e97e2f
commit: c7b55e929b35ccab552f9efd49eed4a168e97e2f
branch: 3.8
author: Miss Islington (bot) <31488909+miss-islington at users.noreply.github.com>
committer: GitHub <noreply at github.com>
date: 2020-04-24T03:04:41-07:00
summary:
Expand the implementation comments (GH-19699) (GH-19701)
files:
M Lib/collections/__init__.py
diff --git a/Lib/collections/__init__.py b/Lib/collections/__init__.py
index cadf1c72f08d4..a78a47c55a8fc 100644
--- a/Lib/collections/__init__.py
+++ b/Lib/collections/__init__.py
@@ -695,6 +695,13 @@ def __repr__(self):
#
# To strip negative and zero counts, add-in an empty counter:
# c += Counter()
+ #
+ # Rich comparison operators for multiset subset and superset tests
+ # are deliberately omitted due to semantic conflicts with the
+ # existing inherited dict equality method. Subset and superset
+ # semantics ignore zero counts and require that p≤q ∧ p≥q → p=q;
+ # however, that would not be the case for p=Counter(a=1, b=0)
+ # and q=Counter(a=1) where the dictionaries are not equal.
def __add__(self, other):
'''Add counts from two counters.
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