Book Image

Python 3 Object Oriented Programming

By : Dusty Phillips
Book Image

Python 3 Object Oriented Programming

By: Dusty Phillips

Overview of this book

Object Oriented Programming is a very important aspect of modern programming languages. The basic principles of Object Oriented Programming are relatively easy to learn. Putting them together into working designs can be challenging.This book makes programming more of a pleasure than a chore using powerful Python 3 object-oriented features of Python 3. It clearly demonstrates the core OOP principles and how to correctly implement OOP in Python. Object Oriented Programming ranks high in importance among the many models Python supports. Yet, many programmers never bother learning the powerful features that make this language object oriented.The book teaches when and how OOP should be correctly applied. It emphasizes not only the simple syntax of OOP in Python, but also how to combine these objects into well-designed software.This book will introduce you to the terminology of the object-oriented paradigm, focusing on object-oriented design with step-by-step examples. It will take you from simple inheritance, one of the most useful tools in the object-oriented programmer's toolbox, all the way through to cooperative inheritance, one of the most complicated. You will be able to raise, handle, define, and manipulate exceptions.You will be able to integrate the object-oriented and the not-so-object-oriented aspects of Python. You will also be able to create maintainable applications by studying higher level design patterns. You'll learn the complexities of string and file manipulation, and how Python distinguishes between binary and textual data. Not one, but two very powerful automated testing systems will be introduced to you. You'll understand the joy of unit testing and just how easy they are to create. You'll even study higher level libraries such as database connectors and GUI toolkits and how they apply object-oriented principles.
Table of Contents (18 chapters)
Python 3 Object Oriented Programming
Credits
About the Author
About the Reviewers
Preface
Index

Extending built-ins


We discussed briefly in Chapter 3 how built-in data types can be extended using inheritance. Now, we'll go into more detail as to when we would want to do that.

When we have a built-in container object that we want to add functionality to, we have two options. We can either create a new object, which holds that container as an attribute (composition), or we can subclass the built-in object and add or adapt methods on it to do what we want (inheritance).

Composition is usually the best alternative if all we want to do is use the container to store some objects using that container's features. That way, it's easy to pass that data structure into other methods and they will know how to interact with it. But we need to use inheritance if we want to change the way the container actually works. For example, if we want to ensure every item in a list is a string with exactly five characters, we need to extend list and override the append() method to raise an exception for invalid...