Python autodict: implicitly create a dictionary instead of raising KeyError + support for object-like dot access + dictionary visitor

autodict.py

# Autodict class
# Create new autodict if accessing undefined key
# support dot access syntax (mydict.test == mydict['test'])
class autodict(dict):
    def __getitem__(self, name):
        if not name in self:
            dict.__setitem__(self, name, autodict())
        return dict.__getitem__(self, name)

    def __getattr__(self, name):
        if name in self.__dict__:
            return self.__dict__[name]
        else:
            return self[name]

    def __setattr__(self, name, val):
        if name in self.__dict__:
            self.__dict__[name] = val
        else:
            self[name] = val




# Visit function for autodict like structure
# Call the given function on each leaf passing all keys in arguments
def visit(obj, func, lvl=-1, args=[]):
    if lvl == 0 or not isinstance(obj, dict):
        func(*(args + [obj]))
    else:
        for key, val in obj.items():
            visit(val, func, lvl - 1, args + [key])

example.txt

Autodicts allow you to use a python dictionary to easily store values with an arbitrary combination of key.
Example:

>>> from autodict import autodict, visit
>>> contact = autodict()
>>> contact.newyork.firends.didier = "3475556677"
>>> contact['newyork']['firends']['ben'] = "3478886677"
>>> contact
{'newyork': {'firends': {'didier': '3475556677', 'ben': '3478886677'}}}

>>> def v(city, role, name, number):
...    print "Number for %s from %s: %s" % (name, city, number)
...

>>> visit(contact, v)
Number for didier from newyork: 3475556677
Number for ben from newyork: 3478886677

Actually, the best approach is to implement missing if you want to subclass a dict.

http://stackoverflow.com/a/19829714/541136