Get to a dictionary's value easily without explicitly checking the existence of previous keys in the dictionary tree.

dictionary.py

class Dictionary(dict):
    '''
    d = Dictionary( {'foo': {'bar': 'foo'}} )
    >>> d['foo']['bar']
    'foo'
    >>> d['foo']['foo']['bar']
    {}
    
    instead of:
    
    if 'foo' in d:
        if 'foo' in d['foo']:
            d['foo']['foo'].get('bar')
    '''
    
    def __getitem__(self, key):
        return self.get(key, Dictionary())
    
    def __setitem__(self, key, val):
        def handle_value(value):
            if isinstance(value, dict):
                return Dictionary( value )
            if isinstance(value, list):
                return [handle_value(i) for i in value]
            return value
        self.update( {key: handle_value( val )} )
    
    def __init__(self, dic={}):  
        for key,val in dic.iteritems():
            self[key] = val