inheritance.md

inheritance

Classes can inherit functionality from other classes, let’s take a look at how that works. We start with a basic class:

class User:
   name = ""

   def __init__(self, name):
       self.name = name

   def printName(self):
       print "Name  = " + self.name

brian = User("brian")
brian.printName()

This creates one instance called brian which outputs its given name. Add another class called Programmer.

class Programmer(User):

    def __init__(self, name):
        self.name = name
    def doPython(self):
        print "Programming Python"

This looks very much like a standard class except than User is given in the parameters. This means all functionality of the class User is accesible in the Programmer class.

Full example of Python inheritance:

class User:
    name = ""

    def __init__(self, name):
        self.name = name

    def printName(self):
        print "Name  = " + self.name

class Programmer(User):
    def __init__(self, name):
        self.name = name

    def doPython(self):
        print "Programming Python"

brian = User("brian")
brian.printName()

diana = Programmer("Diana")
diana.printName()
diana.doPython()

The output:

Name  = brian
Name  = Diana
Programming Python

Brian is an instance of User and can only access the method printName. Diana is an instance of Programmer, a class with inheritance from User, and can access both the methods in Programmer and User.