Class KeyedRef

Lib/weakref.py:277–295

Specialized reference that includes a key corresponding to the value. This is used in the WeakValueDictionary to avoid having to create a function object for each key stored in the mapping. A shared callback object can use the 'key' attribute of a KeyedRef instead of getting a refe

class KeyedRef(ref):
    """Specialized reference that includes a key corresponding to the value.

    This is used in the WeakValueDictionary to avoid having to create
    a function object for each key stored in the mapping.  A shared
    callback object can use the 'key' attribute of a KeyedRef instead
    of getting a reference to the key from an enclosing scope.

    """

    __slots__ = "key",

    def __new__(type, ob, callback, key):
        self = ref.__new__(type, ob, callback)
        self.key = key
        return self

    def __init__(self, ob, callback, key):
        super().__init__(ob, callback)


class WeakKeyDictionary(_collections_abc.MutableMapping):