Modular Programming with Python

Erik Westra

• Publisher: Packt Publishing
• Year: 2016
• eBook ISBN: 9781785884481
• Edition: 1
• Topic: Computer Science
• Subtopic: Programming in Python
• Index: Computer Science

Introducing modular techniques for building sophisticated programs using Python

About This Book

• The book would help you develop succinct, expressive programs using modular deign
• The book would explain best practices and common idioms through carefully explained and structured examples
• It will have broad appeal as far as target audience is concerned and there would be take away for all beginners to Python

Who This Book Is For

This book is intended for beginner to intermediate level Python programmers who wish to learn how to use modules and packages within their programs. While readers must understand the basics of Python programming, no knowledge of modular programming techniques is required.

What You Will Learn

• Learn how to use modules and packages to organize your Python code
• Understand how to use the import statement to load modules and packages into your program
• Use common module patterns such as abstraction and encapsulation to write better programs
• Discover how to create self-testing Python packages
• Create reusable modules that other programmers can use
• Learn how to use GitHub and the Python Package Index to share your code with other people
• Make use of modules and packages that others have written
• Use modular techniques to build robust systems that can handle complexity and changing requirements over time

In Detail

Python has evolved over the years and has become the primary choice of developers in various fields. The purpose of this book is to help readers develop readable, reliable, and maintainable programs in Python.

Starting with an introduction to the concept of modules and packages, this book shows how you can use these building blocks to organize a complex program into logical parts and make sure those parts are working correctly together.

Using clearly written, real-world examples, this book demonstrates how you can use modular techniques to build better programs. A number of common modular programming patterns are covered, including divide-and-conquer, abstraction, encapsulation, wrappers and extensibility. You will also learn how to test your modules and packages, how to prepare your code for sharing with other people, and how to publish your modules and packages on GitHub and the Python Package Index so that other people can use them. Finally, you will learn how to use modular design techniques to be a more effective programmer.

Style and approach

This book will be simple and straightforward, focusing on imparting learning through a wide array of examples that the readers can put into use as they read through the book. They should not only be able to understand the way modules help in improving development, but they should also be able to improvise on their techniques of writing concise and effective code.

Modular Programming with Python

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Table of Contents

Modular Programming with Python

Credits

About the Author

About the Reviewer

www.PacktPub.com

eBooks, discount offers, and more

Why subscribe?

Preface

What this book covers

What you need for this book

Who this book is for

Conventions

Reader feedback

Customer support

Downloading the example code

Errata

Piracy

Questions

1. Introducing Modular Programming

Introducing Python modules

Introducing Python packages

Using modules and packages to organize a program

Why use modular programming techniques?

Programming as a process

The Python Standard Library

Creating your first module

Caching

Writing a cache module

Using the cache

Summary

2. Writing Your First Modular Program

The inventory control system

Designing the inventory control system

The data storage module

The user interface module

The report generator module

The main program

Implementing the inventory control system

Implementing the data storage module

Implementing the user interface module

Implementing the report generator module

Implementing the main program

Summary

3. Using Modules and Packages

Modules and packages

Packages within packages

Initializing a module

Initialization functions

Initializing a package

How to import anything

What does the import statement actually do?

Using the import statement

Relative imports

Controlling what gets imported

Circular dependencies

Running modules from the command line

Summary

4. Using Modules for Real-World Programming

Introducing Charter

Designing Charter

Implementing Charter

Implementing the chart.py module

Implementing the generator.py module

The Pillow library

Renderers

Testing the code

Rendering the title

Rendering the x axis

The remaining renderers

Testing Charter

The fly in the ointment – changing requirements

Redesigning Charter

Refactoring the code

Implementing the PDF renderer modules

Testing the code

Lessons learned

Summary

5. Working with Module Patterns

Divide and conquer

Abstraction

Encapsulation

Wrappers

Extensible modules

Dynamic imports

Plugins

Hooks

Summary

6. Creating Reusable Modules

Using modules and packages to share your code

What makes a module reusable?

Functioning as a standalone unit

Using relative imports

Noting external dependencies

What makes a good reusable module?

Solving a general problem

Following standard conventions

Having clear documentation

Examples of reusable modules

requests

python-dateutil

lxml

Designing a reusable package

Implementing a reusable package

Testing our reusable package

Summary

7. Advanced Module Techniques

Optional imports

Local imports

Tweaking imports using sys.path

Import gotchas

Using an existing name for your module or package

Naming a Python script after a module or package

Adding package directories to sys.path

Executing and importing the same module

Using modules and packages with the Python interactive interpreter

Dealing with global variables

Package configuration

Package data

Summary

8. Testing and Deploying Modules

Testing modules and packages

Testing with the unittest Standard Library module

Designing your unit tests

Code coverage

Test-driven development

Mocking

Writing unit tests for your modules and packages

Preparing a module or package for publication

Uploading your work to GitHub

Submitting to the Python Package Index

Using pip to download and install modules and packages

Summary

9. Modular Programming as a Foundation for Good Programming Technique

The process of programming

The inevitable changes

Change management

Dealing with complexity

Being an effective programmer

Summary

Index

Modular Programming with Python

Copyright © 2016 Packt Publishing

All rights reserved. No part of this book may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, without the prior written permission of the publisher, except in the case of brief quotations embedded in critical articles or reviews.

Every effort has been made in the preparation of this book to ensure the accuracy of the information presented. However, the information contained in this book is sold without warranty, either express or implied. Neither the author, nor Packt Publishing, and its dealers and distributors will be held liable for any damages caused or alleged to be caused directly or indirectly by this book.

Packt Publishing has endeavored to provide trademark information about all of the companies and products mentioned in this book by the appropriate use of capitals. However, Packt Publishing cannot guarantee the accuracy of this information.

First published: May 2016

Production reference: 1200516

Published by Packt Publishing Ltd.

Livery Place

35 Livery Street

Birmingham B3 2PB, UK.

ISBN 978-1-78588-448-1

www.packtpub.com

Credits

Author

Erik Westra

Reviewer

Mike Driscoll

Commissioning Editor

Priya Singh

Acquisition Editor

Dharmesh Parmar

Content Development Editor

Arun Nadar

Technical Editor

Rupali Shrawane

Copy Editor

Sonia Cheema

Project Coordinator

Nikhil Nair

Proofreader

Safis Editing

Indexer

Hemangini Bari

Graphics

Disha Haria

Production Coordinator

Arvindkumar Gupta

Cover Work

Arvindkumar Gupta

About the Author

Erik Westra has been a professional software developer for over 25 years, and has worked almost exclusively in Python for the past decade. Erik's early interest in graphical user interface design led to the development of one of the most advanced urgent courier dispatch systems used by messenger and courier companies worldwide. In recent years, Erik has been involved in the design and implementation of systems matching seekers and providers of goods and services across a range of geographical areas, as well as real-time messaging and payments systems. This work has included the creation of real-time geocoders and map-based views of constantly changing data. Erik is based in New Zealand, and works for companies worldwide.

Erik is also the author of the Packt titles Python Geospatial Development, Python Geospatial Analysis, and Building Mapping Applications with QGIS.

I would like to thank Ruth for being so awesome, and my children for their patience. Without you, none of this would have been possible.

About the Reviewer

Mike Driscoll has been programming in Python since 2006. He enjoys writing about Python on his blog at http://www.blog.pythonlibrary.org/. He co-authored the Core Python Refcard for DZone. Mike has also been a technical reviewer for Python 3 Object Oriented Programming, Python 2.6 Graphics Cookbook, Tkinter GUI Application Development Hotshot, and several others. He recently wrote the book Python 101, and is working on his next book.

I would like to thank my beautiful wife, Evangeline, for always supporting me. I would also like to thank friends and family for all that they do to help me. And I would like to thank Jesus Christ for saving me.

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• Modular Programming with Python