ex44.inheritance-and-composition.py

# Learn Python the Hard Way
# Exercise 44 - Inheritance and Composition

# Using Inheritance
# class Parent(object):
#
#     def override(self):
#         print "PARENT override()"
#
#     def implicit(self):
#         print "PARENT implicit()"
#
#     def altered(self):
#         print "PARENT altered()"
#
# class Child(Parent):
#
#     def __init__(self, stuff):
#         self.stuff = stuff
#         super(Child, self).__init__()
#
#     def override(self):
#         print "CHILD override()"
#
#     def altered(self):
#         print "CHILD, BEFORE PARENT altered()"
#         super(Child, self).altered()
#         print "CHILD, AFTER PARENT altered()"
#
# dad = Parent()
# son = Child()
#
# dad.implicit()
# son.implicit()
#
# dad.override()
# son.override()
#
# dad.altered()
# son.altered()

# Avoiding Inheritance
class Other(object):

    def override(self):
        print "OTHER override()"

    def implicit(self):
        print "OTHER implicit()"

    def altered(self):
        print "OTHER altered()"

class Child(object):

    def __init__(self):
        self.other = Other()

    def implicit(self):
        self.other.implicit()

    def override(self):
        print "CHILD override()"

    def altered(self):
        print "CHILD, BEFORE OTHER altered()"
        self.other.altered()
        print "CHILD, AFTER OTHER altered()"

son = Child()

son.implicit()
son.override()
son.altered()