chain.py

# http://www.testingperspective.com/wiki/doku.php/collaboration/chetan/designpatternsinpython/chain-of-responsibilitypattern

class Handler:
 def successor(self, successor):
 self.successor = successor

class ConcreteHandler1(Handler):
 def handle(self, request):
 if request > 0 and request <= 10:
 print("in handler1")
 else:
 self.successor.handle(request)
 
class ConcreteHandler2(Handler):
 def handle(self, request):
 if request > 10 and request <= 20:
 print("in handler2")
 else:
 self.successor.handle(request)
 
class ConcreteHandler3(Handler):
 def handle(self, request):
 if request > 20 and request <= 30:
 print("in handler3")
 else:
 print('end of chain, no handler for {}'.format(request))
 
class Client:
 def __init__(self):
 h1 = ConcreteHandler1()
 h2 = ConcreteHandler2()
 h3 = ConcreteHandler3()

 h1.successor(h2)
 h2.successor(h3)

 requests = [2, 5, 14, 22, 18, 3, 35, 27, 20]
 for request in requests:
 h1.handle(request)

if __name__== "__main__":
 client = Client()