On Mon, Jan 17, 2022 at 10:14 AM Paul Moore <p.f.mo...@gmail.com> wrote:
>
> On Sun, 16 Jan 2022 at 22:55, Steven D'Aprano <st...@pearwood.info> wrote:
> > >>> def f():
> > ... return frozenset({1, 2, 3})
> > ...
> > >>> a = f.__code__.co_consts[1]
> > >>> a
> > frozenset({1, 2, 3})
> > >>> b = f()
> > >>> assert a == b
> > >>> a is b
> > False
> >
> > Each time you call the function, you get a distinct frozenset object.
>
> I may just be reiterating your point here (if I am, I'm sorry - I'm
> not completely sure), but isn't that required by the definition of the
> frozenset function. You're calling frozenset(), which is defined to
> "Return a new frozenset object, optionally with elements taken from
> iterable". The iterable is the (non-frozen) set {1, 2, 3}.
Where is that definition? According to help(frozenset), it will
"[b]uild an immutable unordered collection of unique elements", so it
doesn't necessarily have to be a brand new object. With mutables, it
does have to return a new one every time (list(x) will give you a
shallow copy of x even if it's already a list), but with immutables,
it's okay to return the same one (str and tuple will return self).
ChrisA
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