On Wed, Jan 5, 2022 at 7:04 AM Marco Sulla <marco.sulla.pyt...@gmail.com> wrote: > > On Tue, 4 Jan 2022 at 19:38, Chris Angelico <ros...@gmail.com> wrote: > > [...] should the keys view be considered > > frozen or not? Remember the set of keys can change (when the > > underlying dict changes). > > Well, also the items can change, but they are returned as tuples with > 2 elements.
That's because a tuple is the correct data type when returning two distinct items. It's not a list that has two elements in it; it's a tuple of (key, value). Immutability is irrelevant. > It seems to me that the stdlib, when something should return a > sequence, prefers to return a tuple. So I expected the same preference > for frozenset over set. Got any examples of variable-length sequences? Usually a tuple is a structure, not just a sequence. If something is just returning a sequence, it'll most often return a dedicated sequence type (like range in Py3) or a list (like lots of things in Py2). ChrisA -- https://mail.python.org/mailman/listinfo/python-list
