There are many ways to implement a Chain of Responsibility in Python, but my favorite implementation is the one by Vespe Savikko (https://legacy.python.org/workshops/1997-10/proceedings/savikko.html). Vespe's implementation uses dynamic dispatching in a Pythonic style to handle requests (http://j.mp/ddispatch).
Let's implement a simple, event-based system using Vespe's implementation as a guide. The following is the UML class diagram of the system:
The Event class describes an event. We'll keep it simple, so in our case, an event has only a name:
class Event:
def __init__(self, name):
self.name = name
def __str__(self):
return self.name
The Widget class is the core class of the application. The parent aggregation shown in the UML diagram indicates that each widget can have a reference to a parent object, which by convention...
