Dict.__missing__ implementation leads to surprising behaviour

[hl037]

All the __parent, __key and __missing__ implementation details lead to surprising behaviors, like this one :

In [1]: from addict import Dict

In [2]: d = Dict()

In [3]: a1 = d.a

In [4]: a2 = d.a

In [5]: a1.b = 1

In [6]: a1.c = 2

In [7]: d
Out[7]: {'a': {'b': 1, 'c': 2}}

In [8]: a2.d = 3

In [9]: d
Out[9]: {'a': {'d': 3}}

In [10]: 

Since I really enjoy this library, I think it may be a good idea to start a discussion on how we could solve the problem.

I though about re-implementing __missing__ with a cache using weakref.WeakValueDictionary for "pending potential child dict". The Idea is to always return the same instance with __missing__, but keeping the current behavior to "really" add it only when a nested key is set (with __setitem__ on the child dict).

Proceeding this way would keep the current behavior of discarding the nested Dict if not used, but avoiding the strange behavior I exposed.

What do you think ? (since I am not a definitive expert with addict, I prefer check with you if there are any stuff I missed, or if there are future plans that would either make this impossible either solve the problem, before implementing it myself)

[Salvakiya]

has there been any investigation into this?