Python Modules

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A module is a file containing Python definitions and statements. The file name is the module name with the suffix .py appended. Modules allow you to organize your code logically and reuse it in other programs.

Creating and Using Modules

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To create a module, you simply save the code you want in a file with a .py extension.

mymodule.py:

def greeting(name):
  print(f"Hello, {name}")

person1 = {
  "name": "John",
  "age": 36,
  "country": "Norway"
}

You can use the import statement to use the module in another program.

main.py:

import mymodule

mymodule.greeting("Jonathan")  # "Hello, Jonathan"

a = mymodule.person1["age"]
print(a)  # 36

Importing From a Module

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You can choose to import only specific parts from a module by using the from keyword.

from mymodule import person1

print(person1["age"])  # 36

The __name__ Attribute

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The __name__ attribute of a module is a special variable that is set to “main” when the module is run as the main program, and to the module's name when it is imported.

# mymodule.py
if __name__ == "__main__":
    print("This module is being run directly.")
else:
    print("This module is being imported.")

This is often used to provide a command-line interface to a module.

Packages

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Packages are a way of structuring Python’s module namespace by using “dotted module names”. A package is a directory of Python modules containing an additional __init__.py file, which can be empty or can execute initialization code for the package.