initial creation

py3interm/EXAMPLES/abstract_base_classes.py

@@ -0,0 +1,32 @@
+#!/usr/bin/env python
+#
+from abc import ABCMeta, abstractmethod
+
+class Animal(metaclass=ABCMeta):  # <1>
+
+    @abstractmethod   # <2>
+    def speak(self):
+        pass
+
+class Dog(Animal):  # <3>
+    def speak(self):   # <4>
+        print("woof! woof!")
+
+class Cat(Animal):  # <3>
+    def speak(self):  # <4>
+        print("Meow meow meow")
+
+class Duck(Animal): # <3>
+    pass  # <5>
+
+d = Dog()
+d.speak()
+
+c = Cat()
+c.speak()
+
+try:
+    d = Duck()  # <6>
+    d.speak()
+except TypeError as err:
+    print(err)