Book Image

Raspberry Pi for Python Programmers Cookbook - Second Edition

Book Image

Raspberry Pi for Python Programmers Cookbook - Second Edition

Overview of this book

Raspberry Pi cookbook for Python Programmers is a practical guide for getting the most out of this little computer. This book begins by guiding you through setting up the Raspberry Pi, performing tasks using Python 3 and introduces the first steps to interface with electronics. As you work through each chapter you will build up your skills and knowledge and apply them as you progress throughout the book, delving further and further into the unique abilities and features of the Raspberry Pi. Later, you will learn how to automate tasks by accessing files, build applications using the popular Tkinter library and create games by controlling graphics on screen. You will harness the power of the built-in graphics processor by using Pi3D to generate your own high quality 3D graphics and environments. Connect directly to the Raspberry Pi’s hardware pins to control electronics from switching on LEDs and responding to push buttons right through to driving motors and servos. Learn how to monitor sensors to gather real life data and to use it to control other devices, and view the results over the Internet. Apply what you have learnt by creating your own Pi-Rover or Pi-Hexipod robots. Finally, we will explore using many of the purpose built add-ons available for the Raspberry Pi, as well as interfacing with common household devices in new ways.
Table of Contents (18 chapters)
Raspberry Pi for Python Programmers Cookbook - Second Edition
Credits
About the Author
About the Reviewer
www.PacktPub.com
Preface
Hardware and Software List
Index

Using files and handling errors


In addition to easy string handling, Python allows you to read, edit, and create files easily. So, by building upon the previous scripts, we can make use of our encryptText() function to encode complete files.

Reading and writing to files can be quite dependent on factors that are outside of the direct control of the script, such as whether the file that we are trying to open exists or the filesystem has space to store a new file. Therefore, we will also take a look at how to handle exceptions and protect operations that may result in errors.

Getting ready

The following script will allow you to specify a file through the command line, which will be read and encoded to produce an output file. Create a small text file named infile.txt and save it so that we can test the script. It should include a short message similar to the following:

This is a short message to test our file encryption program.

How to do it…

Create the fileencrypt.py script using the following code...