[issue34719] Deprecate set to frozenset conversion in set.__contains__

Raymond Hettinger added the comment: The feature was first implemented in Lib/sets.py (arising from PEP 218) in pure python. It was found to be useful and carried forward to the C implementation for the built-in type. The feature is documented but not highlighted in the Library Reference,

[issue34719] Deprecate set to frozenset conversion in set.__contains__

Change by Raymond Hettinger : -- versions: -Python 2.7, Python 3.4, Python 3.5, Python 3.6, Python 3.7 ___ Python tracker ___ ___

[issue34719] Deprecate set to frozenset conversion in set.__contains__

Change by Raymond Hettinger : -- assignee: -> rhettinger nosy: +rhettinger ___ Python tracker ___ ___ Python-bugs-list mailing

[issue34719] Deprecate set to frozenset conversion in set.__contains__

Change by Karthikeyan Singaravelan : -- nosy: +xtreak ___ Python tracker ___ ___ Python-bugs-list mailing list Unsubscribe:

[issue34719] Deprecate set to frozenset conversion in set.__contains__

New submission from Javier Dehesa : This comes from this SO question: https://stackoverflow.com/q/52382983/1782792 Currently, this works: > print({1, 2} in {frozenset({1, 2})) # True This is strange because set is unhashable. Apparently, it is a case-specific feature implemented back