Update chain pattern with coroutine realization

Author: mlyundin

chain.py

@@ -2,13 +2,19 @@
 # -*- coding: utf-8 -*-
 
 """http://www.testingperspective.com/wiki/doku.php/collaboration/chetan/designpatternsinpython/chain-of-responsibilitypattern"""
+"""http://www.dabeaz.com/coroutines/"""
+
+import time
+import os
+import sys
+from contextlib import contextmanager
 
 class Handler:
-    def __init__(self,successor):
-        self._successor = successor;
-    def handle(self,request):
-        i = self._handle(request)
-        if  not i:
+    def __init__(self, successor=None):
+        self._successor = successor
+    def handle(self, request):
+        res = self._handle(request)
+        if not res:
             self._successor.handle(request)
     def _handle(self, request):
         raise NotImplementedError('Must provide implementation in subclass.')
@@ -43,16 +49,95 @@ def _handle(self, request):
 
 class Client:
     def __init__(self):
-        self.handler = ConcreteHandler1(ConcreteHandler3(ConcreteHandler2(DefaultHandler(None))))
+        self.handler = ConcreteHandler1(ConcreteHandler3(ConcreteHandler2(DefaultHandler())))
     def delegate(self, requests):
         for request in requests:
             self.handler.handle(request)
 
 
+def coroutine(func):
+    def start(*args, **kwargs):
+        cr = func(*args, **kwargs)
+        cr.next()
+        return cr
+    return start
+
+@coroutine
+def coroutine1(target):
+    while True:
+        request = yield
+        if 0 < request <= 10:
+            print('request {} handled in coroutine 1'.format(request))
+        else:
+            target.send(request)
+
+@coroutine
+def coroutine2(target):
+    while True:
+        request = yield
+        if 10 < request <= 20:
+            print('request {} handled in coroutine 2'.format(request))
+        else:
+            target.send(request)
+
+@coroutine
+def coroutine3(target):
+    while True:
+        request = yield
+        if 20 < request <= 30:
+            print('request {} handled in coroutine 3'.format(request))
+        else:
+            target.send(request)
+
+@coroutine
+def default_coroutine():
+        while True:
+            request = yield
+            print('end of chain, no coroutine for {}'.format(request))
+
+class ClientCoroutine:
+    def __init__(self):
+        self.target = coroutine1(coroutine3(coroutine2(default_coroutine())))
+
+    def delegate(self, requests):
+        for request in requests:
+            self.target.send(request)
+
+def timeit(func):
+
+    def count(*args, **kwargs):
+        start = time.time()
+        res = func(*args, **kwargs)
+        count._time = time.time() - start
+        return res
+    return count
+
+@contextmanager
+def suppress_stdout():
+    try:
+        stdout, sys.stdout = sys.stdout, open(os.devnull, 'w')
+        yield
+    finally:
+        sys.stdout = stdout
+
+
 if __name__ == "__main__":
-    client = Client()
+    client1 = Client()
+    client2 = ClientCoroutine()
     requests = [2, 5, 14, 22, 18, 3, 35, 27, 20]
-    client.delegate(requests)
+
+    client1.delegate(requests)
+    print('-'*30)
+    client2.delegate(requests)
+
+    requests *= 10000
+    client1_delegate = timeit(client1.delegate)
+    client2_delegate = timeit(client2.delegate)
+    with suppress_stdout():
+        client1_delegate(requests)
+        client2_delegate(requests)
+    # lets check what is faster
+    print(client1_delegate._time, client2_delegate._time)
 
 ### OUTPUT ###
 # request 2 handled in handler 1
@@ -64,3 +149,14 @@ def delegate(self, requests):
 # end of chain, no handler for 35
 # request 27 handled in handler 3
 # request 20 handled in handler 2
+# ------------------------------
+# request 2 handled in coroutine 1
+# request 5 handled in coroutine 1
+# request 14 handled in coroutine 2
+# request 22 handled in coroutine 3
+# request 18 handled in coroutine 2
+# request 3 handled in coroutine 1
+# end of chain, no coroutine for 35
+# request 27 handled in coroutine 3
+# request 20 handled in coroutine 2
+# (0.2369999885559082, 0.16199994087219238)