Book Image

Modular Programming with Python

By : Erik Westra
Book Image

Modular Programming with Python

By: Erik Westra

Overview of this book

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.
Table of Contents (16 chapters)
Modular Programming with Python
About the Author
About the Reviewer

Initializing a module

When a module is imported, any top-level code within that module is executed. This has the effect of making the various functions, variables, and classes you defined in your module available for the caller to use. To see how this works, create a new Python source file named, and enter the following code into this module:

def foo():
    print("in foo")

def bar():
    print("in bar")

my_var = 0

print("importing test module")

Now, open up a terminal window, cd into the directory where your file is stored, and type python to start up the Python interpreter. Then try typing the following:

% import test_module

When you do this, the Python interpreter prints the following message:

importing test module

It does this because all the top-level Python statements in the module—including the def statements and our print statement—are executed when the module is imported. You can then call the foo and bar functions, and access the my_var global, by prefixing...