This is found in the python standard library, as unittest.TestLoader.loadTestsFromName. Unfortunately, the method goes on to do additional test-related activities, but this first ha looks re-usable. We have edited it to remove the test-related functionality:
def get_object(name):
    """Retrieve a python object, given its dotted.name."""
    parts = name.split('.')
    parts_copy = parts[:]
    while parts_copy:
        try:
            module = __import__('.'.join(parts_copy))
            break
        except ImportError:
            del parts_copy[-1]
            if not parts_copy: raise
    parts = parts[1:]
    obj = module
    for part in parts:
        parent, obj = obj, getattr(obj, part)
    return obj