resolving_dict.py

#!/usr/bin/env python
import collections

class ResolvingDict(collections.MutableMapping):
    """Find a key in current or parent node"""
    def __init__(self, mapping, parent=None):
        self.store = dict()
        self.update(mapping)
        self.parent = parent

    def __setitem__(self, key, value):
        self.store[key] = value

    def __getitem__(self, item):
        
        if self.parent and item not in self.store:
            value = self.parent[item]
        else:
            value = self.store[item]

        if hasattr(value, "__iter__"):
            return ResolvingDict(value, parent=self)
        else:
            return value

    def __delitem__(self, key):
        del(self.store[key])

    def __iter__(self):
        return iter(self.store)

    def __len__(self):
        return len(self.store)

    def __repr__(self):
        return str(self.store)

if __name__ == "__main__":
    
    d = {
        "key1": "value1",
        "key2": "value2",
        "node1": {
            "key1": "value1.1"
        }
    }
    
    d = ResolvingDict(d)
    print d["node1"]["key2"]