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Raspberry Pi 3 Cookbook for Python Programmers - Third Edition
book

Raspberry Pi 3 Cookbook for Python Programmers - Third Edition

by Steven Lawrence Fernandes, Tim Cox
April 2018
Beginner content levelBeginner
552 pages
13h 58m
English
Packt Publishing
Content preview from Raspberry Pi 3 Cookbook for Python Programmers - Third Edition

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The first script defines a class called Switch; it sets up the GPIO pins required to control the five relays (within the setup function). It also defines the __enter__ and __exit__ functions, which are special functions used by the with..as statement. When a class is created using with..as, it uses __enter__ to perform any extra initialization or setup (if required), and then it performs any cleanup by calling __exit__. When the Switch class has been executed, all the relays are switched off to preserve the remote's battery and GPIO.cleanup() is called to release the GPIO pins. The parameters of the __exit__ function (type, value, and traceback) allow the handling of any specific exceptions that may have occurred when the ...

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Publisher Resources

ISBN: 9781788629874Supplemental Content