📝 Inheritance#

  • Inheritance allows one class to inherit properties from another class.

  • It is usually referred to as child and parent classes.

  • It allows you to better represent real-world relationships.

  • Code can become much more reusable.

  • It is transitive meaning that if Class B inherits from Class A then subclasses of Class B would also inherit from Class A.

Inheritance Example#

Syntax

Class BaseClass: {Body} Class DerivedClass(BaseClass): {Body}

Step 1: Create a parent class with a method#

  • Create a parent class named Person that defines a name and age

  • Add a Class method that prints the name and title

class Person:

    # Constructor
    def __init__(self, name, age):
        self.name = name
        self.age = age

    # To check if this person is an employee
    def Display(self):
        print(self.name, self.age)

Testing#

jedi = Person("Darth Vader", 56)
jedi.Display()

Darth Vader 56

Step 2: Creating a Child Class;#

  • Create a child class of Person, Jedi that has a method Print that prints Jedi's use the force

class Jedi(Person):
    def Print(self):
        print("Jedi's use the force")

Testing#

# instantiate the parent class
jedi_info = Jedi("Darth Vader", 56)

# calls the parent class
jedi_info.Display()

# calls the child class
jedi_info.Print()

Darth Vader 56
Jedi's use the force

Step 3: Adding Inheritance#

  • Starting with the base Class Person we can add a method to getName that returns the name

  • We can add a method isAlliance that establishes if the person is part of the Rebel Alliance, the default should be False

  • We can add a inherited child class Alliance that changes isAlliance to True

class Person:

    # Constructor
    def __init__(self, name, age):
        self.name = name
        self.age = age

    # Function that gets the name
    def getName(self):
        return self.name

    # Function that returns if the person is part of the alliance
    def isAlliance(self):
        return False


# Inherited child class
class Alliance(Person):

    # This will change the isAlliance class to True
    def isAlliance(self):
        return True

Test#

darth_vader = Person("Darth Vader", 56)
print(darth_vader.getName(), darth_vader.isAlliance())

luke_skywalker = Alliance("Luke Skywalker", 21)
print(luke_skywalker.getName(), luke_skywalker.isAlliance())

Darth Vader False
Luke Skywalker True