[issue38756] Add generic versions of weakref types to typing module
Nils Kattenbeck
report at bugs.python.org
Sat Nov 9 19:20:51 EST 2019
Nils Kattenbeck <nilskemail at gmail.com> added the comment:
A possible use case would be having multiple users and some groups said users can belong to. When using a WeakSet a user won't be part of a groups after he deleted his account without having to iterate over all groups.
class User: pass
class Group:
users: WeakSet[User]
def __init__(self, users: Iterable[User]):
self.users = WeakSet(users)
# somewhere else a collection of all active users
Types I would like to see added as a generic would be primarily:
- WeakKeyDictionary
- WeakValueDictionary
- WeakSet
Additionally it would be nice to have generic versions of:
- ref (would probably return Optional[T] on call?)
- WeakMethod
- ProxyType
- CallableProxyType
Although the last two could probably be just annotated using T because they mostly should behave the same...
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<https://bugs.python.org/issue38756>
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