Abstract Classes in Python

Yang Zhou
Yang Zhou
May 18, 2020 · 2 min read
Photo by Photo Boards on Unsplash

Introduction

Abstract Class is a very important concept of object-oriented programming. It is a good practice of DRY (Don’t Repeat Yourself) principle. In a large project, code duplication is approximately equal to bug reuse and one developer is impossible to remember all classes’ details. Therefore, it’s very helpful to use an abstract class to define a common interface for different implementations.

  • An abstract class cannot be instantiated. It just provides an interface for subclasses to avoid code duplication. It makes no sense to instantiate an abstract class.
  • A derived subclass must implement the abstract methods to create a concrete class that fits the interface defined by the abstract class. Therefore it cannot be instantiated unless all of its abstract methods are overridden.

Define Abstract Class in Python

Python comes with a module called abc which provides useful stuff for abstract class.

Invoke Methods from Abstract Classes

Actually an abstract method is not needed to be “totally abstract” in Python, which is different with some other object-oriented programming language. We can define some common stuff in an abstract method and use super() to invoke it in subclasses.

Photo by Alexander Schimmeck on Unsplash

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