This module provides the Observable class
Handles subject/observer notifications.
Automatically register all class-scope message names.
There are two rules at play here:
Message names must be defined at class scope. e.g.:
- class Foo(object):
message_foo = ‘foo’
Message name variables must begin with the string ‘message_‘
Providing a ‘messages’ dict avoids this built-in behavior but does not guarantee that the messages names are registered for clones or unserialized objects.