Python data structure for a collection of objects with random access based on an attribute

Question

I need a collection of objects which can be looked up by a certain (unique) attribute common to each of the objects. Right now I am using a dicitionary assigning the dictionary

Answer 1

There are a number of great things you can do here. One example would be to let the class keep track of everything:

class Item():
    _member_dict = {}
    @classmethod
    def get_by_key(cls,key):
        return cls._member_dict[key]
    def __init__(self, uniq_key, title=None):
        self.key = uniq_key
        self.__class__._member_dict[key] = self
        self.title = title

>>> i = Item('foo')
>>> i == Item.get_by_key('foo')
True

Note you will retain the update problem: if key changes, the _member_dict falls out of sync. This is where encapsulation will come in handy: make it (practically) impossible to change key without updating the dictionary. For a good tutorial on how to do that, see this tutorial.