pazdera · August 15, 2011 07:38 · Aug 15, 2011
diff --git a/adapter.py b/adapter.py
@@ -0,0 +1,96 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+# Example of `adapter' design pattern
+# Copyright (C) 2011 Radek Pazdera
+
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+
+# Adaptee (source) interface
+class EuropeanSocketInterface:
+    def voltage(self): pass
+
+    def live(self): pass
+    def neutral(self): pass
+    def earth(self): pass
+
+# Adaptee
+class Socket(EuropeanSocketInterface):
+    def voltage(self):
+        return 230
+
+    def live(self):
+        return 1
+
+    def neutral(self):
+        return -1
+
+    def earth(self):
+        return 0
+
+# Target interface
+class USASocketInterface:
+    def voltage(self): pass
+
+    def live(self): pass
+    def neutral(self): pass
+
+# The Adapter
+class Adapter(USASocketInterface):
+    __socket = None
+
+    def __init__(self, socket):
+        self.__socket = socket
+
+    def voltage(self):
+        return 110
+
+    def live(self):
+        return self.__socket.live()
+
+    def neutral(self):
+        return self.__socket.neutral()
+
+# Client
+class ElectricKettle:
+    __power = None
+
+    def __init__(self, power):
+        self.__power = power
+
+    def boil(self):
+        if self.__power.voltage() > 110:
+            print "Kettle on fire!"
+        else:
+            if self.__power.live()    == 1 and \
+               self.__power.neutral() == -1:
+                print "Coffee time!"
+            else:
+                print "No power."
+
+
+def main():
+    # Plug in
+    socket  = Socket()
+    adapter = Adapter(socket)
+    kettle  = ElectricKettle(adapter)
+
+    # Make coffee
+    kettle.boil()
+
+    return 0
+
+if __name__ == "__main__":
+    main()
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