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Learning Python

You're reading from  Learning Python

Product type Book
Published in Dec 2015
Publisher Packt
ISBN-13 9781783551712
Pages 442 pages
Edition 1st Edition
Languages
Author (1):
Fabrizio Romano Fabrizio Romano
Profile icon Fabrizio Romano
Toc

Table of Contents (20) Chapters close

Learning Python
Credits
About the Author
Acknowledgements
About the Reviewers
www.PacktPub.com
Preface
1. Introduction and First Steps – Take a Deep Breath 2. Built-in Data Types 3. Iterating and Making Decisions 4. Functions, the Building Blocks of Code 5. Saving Time and Memory 6. Advanced Concepts – OOP, Decorators, and Iterators 7. Testing, Profiling, and Dealing with Exceptions 8. The Edges – GUIs and Scripts 9. Data Science 10. Web Development Done Right 11. Debugging and Troubleshooting 12. Summing Up – A Complete Example Index

Scopes and name resolution


Do you remember when we talked about scopes and namespaces in the first chapter? We're going to expand on that concept now. Finally, we can talk about functions and this will make everything easier to understand. Let's start with a very simple example.

scoping.level.1.py

def my_function():
    test = 1 # this is defined in the local scope of the function
    print('my_function:', test)

test = 0  # this is defined in the global scope
my_function()
print('global:', test)

I have defined the name test in two different places in the previous example. It is actually in two different scopes. One is the global scope (test = 0), and the other is the local scope of the function my_function (test = 1). If you execute the code, you'll see this:

$ python scoping.level.1.py
my_function: 1
global: 0

It's clear that test = 1 shadows the assignment test = 0 in my_function. In the global context, test is still 0, as you can see from the output of the program but we define the name...

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