Incomplete return type for ipaddress.IPv4Network.hosts()

[elWanderero]

Documentation

(And also for ipaddress.IPv6Network.hosts())

In https://docs.python.org/3/library/ipaddress.html#ipaddress.IPv4Network.hosts and https://docs.python.org/3/library/ipaddress.html#ipaddress.IPv6Network.hosts the hosts() method is documented as returning an iterator, when in reality it can return an iterator or a list.

This extra return possibilty can be seen in

cpython/Lib/ipaddress.py

Line 1549 in 781cc68

self.hosts = lambda: [IPv4Address(addr)]

and

cpython/Lib/ipaddress.py

Line 2340 in 781cc68

self.hosts = lambda: [IPv6Address(addr)]

and was introduced in 2020 in 8e9c47a, but was fixed only recently in typeshed: python/typeshed@c0fed91

Linked PRs

• gh-141497: make ipaddress.IP{v4,v6}Network.hosts() return an iterator #141547
• [3.14] gh-141497: Make ipaddress.IP{v4,v6}Network.hosts() always returning an iterator (GH-141547) #141673

[serhiy-storchaka]

Returning an iterator or a list looks bad design. It should either always return an iterator (so next() works) or a re-iterable iterable.

I think that we can consider 8e9c47a introducing a bug. hosts should return not [IPv4Address(addr)], but iter([IPv4Address(addr)]).

[XChaitanyaX]

working on this...