add Facade pattern

Author: JakubVojvoda

facade/Facade.py

@@ -0,0 +1,51 @@
+#
+# Python Design Patterns: Facade
+# Author: Jakub Vojvoda [github.com/JakubVojvoda]
+# 2016
+#
+# Source code is licensed under MIT License
+# (for more details see LICENSE)
+# 
+
+import sys
+
+#
+# Subsystems
+# implement more complex subsystem functionality
+# and have no knowledge of the facade
+#
+class SubsystemA:
+  def suboperation(self):
+    print("Subsystem A method")
+
+class SubsystemB:
+  def suboperation(self):
+    print("Subsystem B method")
+
+class SubsystemC:
+  def suboperation(self):
+    print("Subsystem C method")
+
+#
+# Facade
+# delegates client requests to appropriate subsystem object
+# and unified interface that is easier to use
+#
+class Facade:
+  def __init__(self):
+    self._subA = SubsystemA()
+    self._subB = SubsystemB()
+    self._subC = SubsystemC()
+
+  def operation1(self):
+    self._subA.suboperation()
+    self._subB.suboperation()
+
+  def operation2(self):
+    self._subC.suboperation()
+
+
+if __name__ == "__main__":
+  facade = Facade()
+  facade.operation1()
+  facade.operation2()