Coding Subclasses

As a next step, then, let’s put OOP’s methodology to use and customize our Person class by extending our software hierarchy. For the purpose of this tutorial, we’ll define a subclass of Person called Manager that replaces the inherited giveRaise method with a more specialized version. Our new class begins as follows:

class Manager(Person):                          # Define a subclass of Person

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This code means that we’re defining a new class named Manager, which inherits from and may add customizations to the superclass Person. In plain terms, a Manager is almost like a Person (admittedly, a very long journey for a very small joke...), but Manager has a custom way to give raises.

For the sake of argument, let’s assume that when a Manager gets a raise, it receives the passed-in percentage as usual, but also gets an extra bonus that defaults to 10%. For instance, if a Manager’s raise is specified as 10%, it will really get 20%. (Any relation to Persons living or dead is, of course, strictly coincidental.) Our new method begins as follows; because this redefinition of giveRaise will be closer in the class tree to Manager instances than the original version in Person, it effectively replaces, and thereby customizes, the operation. Recall that according to the inheritance search rules, the lowest version of the name wins:

class Manager(Person):                          # Inherit Person attrs
    def giveRaise(self, percent, bonus=.10):    # Redefine to customize