Inheritance

Last updated Nov 21, 2022

• Technology
• Programming

A feature that allows the derivation of a new class from an existing class. Introduces a way to reuse existing code without duplicating them.

A subclass inherits all the functionality of a superclass, but can also have its own unique attributes and methods.

In many OOP-based languages, a subclass can be created using the : symbol as such:

• C#

1
2
3
4
5
6

// CashCard is an existing class that is the superclass.
// MemberCashCard is the new class deriving from CashCard.
class MemberCashCard: CashCard
{
	// Unique attributes, properties, and methods
}

• Python

1
2
3
4

# CashCard is an existing class that is the superclass.
# MemberCashCard is the new class deriving from CashCard.
class MemberCashCard(CashCard):
	# Unique attributes, properties, and methods

A subclass can call upon the superclasses’s attributes and properties, though the exact method differs across programming languages.

Some examples when inheriting superclass is used include:

• calling the superclass’s constructors to initialise the attributes in the superclass;

• calling the superclass’s printing method to retrieve information in the superclass; and

• calling a method in the superclass.

• C#

1
2
3
4
5

// Defining the constructor for MySubClass
public MySubClass(subparams) : base(superparams)
{
	// other initialization
}