gistfile1.py

class BigStorageClass(object):
    '''Class that will represent a large data blob that contains lots of smaller child objects'''
    def lookup_something(self, **kwargs):
        some_data = self.do_something_with(kwargs)
        return some_data

class SmallChildObject(object):
    '''Instantiation of this class needs to look up something in an instance of the BigStorageClass. Clearly,
    I don't want to make BigStorageClass a child of SmallChildObject. Is there a way to pass in the *name* of
    the BigStorageClass instance as a string and get the instance?'''
    def __init__(self, ref_to_storage)
        self.look_in_storage_class(ref_to_storage)
    
    def look_in_storage_class(self, classname):
        storage_class = get_instance_by(classname)
        return storage_class(...)

bigdata = BigStorageClass(...)
''' do some stuff to put lots of data in bigdata '''
smallobj = SmallChildObject(self, 'bigdata')