You could create such a class with a few lines of code by inheriting from collections.abc.MutableSet You as anyone with a pontual problem that would benefit from such a construct - I can't see why/when this would be useful unless in a project already dealing with symbolic/lazy mathematical concepts - in which case, the author would be already aware of these possibilities. On Mon, 10 Aug 2020 at 08:23, haael <haael@interia.pl> wrote:
Forgive me if this has already been discussed.
Could we add the idea of "negative" sets to Python? That means sets that contain EVERYTHING EXCEPT certain elements.
First, let's have a universal set that contains everything.
assert element in set.UNIVERSAL
The universal set is a superset of every other set.
assert set.UNIVERSAL >= any_set
Adding anything to universal set doesn't change anything.
assert set.UNIVERSAL | element == set.UNIVERSAL
However REMOVING an element from the set puts it on "negative list".
myset = set.UNIVERSAL myset.remove(element) assert element not in myset
Intersection of a "negative set" with a normal set gives again a normal set. Union of two negative sets, or a negative set with a normal set, gives a negative set.
The main issue: negative sets would not be iterable, but you can intersect them with the desired subdomain and iterate over. _______________________________________________ Python-ideas mailing list -- python-ideas@python.org To unsubscribe send an email to python-ideas-leave@python.org https://mail.python.org/mailman3/lists/python-ideas.python.org/ Message archived at https://mail.python.org/archives/list/python-ideas@python.org/message/MY77JS... Code of Conduct: http://python.org/psf/codeofconduct/