Book Image

Python Object-Oriented Programming - Fourth Edition

By : Steven F. Lott, Dusty Phillips
2 (1)
Book Image

Python Object-Oriented Programming - Fourth Edition

2 (1)
By: Steven F. Lott, Dusty Phillips

Overview of this book

Object-oriented programming (OOP) is a popular design paradigm in which data and behaviors are encapsulated in such a way that they can be manipulated together. Python Object-Oriented Programming, Fourth Edition dives deep into the various aspects of OOP, Python as an OOP language, common and advanced design patterns, and hands-on data manipulation and testing of more complex OOP systems. These concepts are consolidated by open-ended exercises, as well as a real-world case study at the end of every chapter, newly written for this edition. All example code is now compatible with Python 3.9+ syntax and has been updated with type hints for ease of learning. Steven and Dusty provide a comprehensive, illustrative tour of important OOP concepts, such as inheritance, composition, and polymorphism, and explain how they work together with Python’s classes and data structures to facilitate good design. In addition, the book also features an in-depth look at Python’s exception handling and how functional programming intersects with OOP. Two very powerful automated testing systems, unittest and pytest, are introduced. The final chapter provides a detailed discussion of Python's concurrent programming ecosystem. By the end of the book, you will have a thorough understanding of how to think about and apply object-oriented principles using Python syntax and be able to confidently create robust and reliable programs.
Table of Contents (17 chapters)
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Creating an abstract base class

Imagine we are creating a media player with third-party plugins. It is advisable to create an abstract base class (ABC) in this case to document what API the third-party plugins should provide (documentation is one of the stronger use cases for ABCs).

The general design is to have a common feature, like play(), that applies to a number of classes. We don't want to pick some particular media format to use as a superclass; it seems somehow wrong to claim that some format is foundational, and all others are derived from it.

We'd prefer to define the media player as an abstraction. Each unique kind of media file format can provide a concrete implementation of the abstraction.

The abc module provides the tools to do this. Here's an abstract class that requires a subclass to provide a concrete method and a concrete property to be useful:

class MediaLoader(abc.ABC):
    def play(self) -&gt...