Modules and packages¶

Module is a Python source code file, i.e. a file with .py extension.

Package is a directory which contains __init__.py file and can contain python modules and other packages.

Why to organize your code into modules and packages¶

• Maintainability
• Reusability
• Namespacing
• People unfamiliar with your project can get a clear overview just by looking at the directory structure of your project
• Searching for certain functionality or class is easy

How to use¶

Let's use the following directory structure as an example:

food_store/ __init__.py product/ __init__.py fruit/ __init__.py apple.py banana.py drink/ __init__.py juice.py milk.py beer.py cashier/ __ini__.py receipt.py calculator.py 

Let's consider that banana.py file contains:

def get_available_brands(): return ["chiquita"] class Banana: def __init__(self, brand="chiquita"): if brand not in get_available_brands(): raise ValueError(f"Unknown brand: {brand}") self._brand = brand 

Importing¶

Let's say that we need access Banana class from banana.py file inside receipt.py. We can achive this by importing at the beginning of receipt.py:

from food_store.product.fruit.banana import Banana # then it's used like this my_banana = Banana() 

If we need to access multiple classes or functions from banana.py file:

from food_store.product.fruit import banana # then it's used like this brands = banana.get_available_brands() my_banana = banana.Banana() 

A comprehensive introduction to modules and packages can be found here.