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Learn Python Programming, 3rd edition

You're reading from   Learn Python Programming, 3rd edition An in-depth introduction to the fundamentals of Python

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Product type Paperback
Published in Oct 2021
Publisher Packt
ISBN-13 9781801815093
Length 554 pages
Edition 3rd Edition
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Authors (2):
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Heinrich Kruger Heinrich Kruger
Author Profile Icon Heinrich Kruger
Heinrich Kruger
Fabrizio Romano Fabrizio Romano
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Fabrizio Romano
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Table of Contents (18) Chapters Close

Preface 1. A Gentle Introduction to Python 2. Built-In Data Types FREE CHAPTER 3. Conditionals and Iteration 4. Functions, the Building Blocks of Code 5. Comprehensions and Generators 6. OOP, Decorators, and Iterators 7. Exceptions and Context Managers 8. Files and Data Persistence 9. Cryptography and Tokens 10. Testing 11. Debugging and Profiling 12. GUIs and Scripting 13. Data Science in Brief 14. Introduction to API Development 15. Packaging Python Applications 16. Other Books You May Enjoy
17. Index

Scopes and name resolution

Do you remember when we talked about scopes and namespaces in Chapter 1, A Gentle Introduction to Python? We're going to expand on that concept now. Finally, we can talk in terms of 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)

We have defined the test name 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 my_function() function (test = 1). If we execute the code, we will see this:

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

It's clear that test = 1 shadows the test = 0 assignment in my_function...

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