Modules and Packages

What Are Modules and Packages?

Imagine you have a huge box of LEGO bricks. Building something big and complex would be hard if all the pieces were mixed up. So, you might want to organize them into smaller boxes: one for wheels, one for windows, one for doors, etc. This makes it much easier to find the pieces you need.

In Python, a module is like one of those smaller boxes. It’s a file that contains some Python code, such as functions, variables, or classes, that you can use in your programs. A package is like a bigger box that contains several modules. It’s a way to organize your code into folders and subfolders.

Why Use Modules and Packages?

1. Organization: Just like sorting your LEGO bricks, modules and packages help keep your code neat and tidy.
2. Reuse: You can use the same module in different programs without rewriting the code.
3. Maintenance: It’s easier to find and fix bugs when your code is organized into smaller, manageable pieces.

Creating and Using a Module

Let’s start by creating a simple module.

1. Create a Module: Open your text editor and write the following code:

# my_module.py

def greet(name):
    return f"Hello, {name}!"

PI = 3.14159

2. Save the File: Save this file as my_module.py. Now you have a module!
3. Use the Module: You can use this module in another Python file.

# main.py

import my_module

print(my_module.greet("Alice"))
print("The value of PI is:", my_module.PI)

When you run main.py, you will see:

Hello, Alice!
The value of PI is: 3.14159

Creating and Using a Package

Now, let’s create a package. A package is a folder that contains multiple modules.

1. Create a Package Folder: Create a new folder named my_package.
2. Add an __init__.py File: Inside my_package, create a file named __init__.py. This file can be empty, but it tells Python that this folder is a package.
3. Add Modules to the Package: Create two modules inside my_package:

# my_package/math_operations.py

def add(a, b):
    return a + b

def subtract(a, b):
    return a - b

# my_package/string_operations.py

def uppercase(text):
    return text.upper()

def lowercase(text):
    return text.lower()

4. Use the Package: Now you can use these modules in another Python file.

# main.py

from my_package import math_operations, string_operations

print(math_operations.add(5, 3))
print(math_operations.subtract(10, 4))

print(string_operations.uppercase("hello"))
print(string_operations.lowercase("WORLD"))

When you run main.py, you will see:

8
6
HELLO
world

Practice Questions

1. Question: Create a module named calculator.py with functions to multiply and divide two numbers. Then, use these functions in another Python file.

Solution:

# calculator.py

def multiply(a, b):
    return a * b

def divide(a, b):
    if b != 0:
        return a / b
    else:
        return "Cannot divide by zero!"

# main.py

import calculator

print(calculator.multiply(6, 7))
print(calculator.divide(10, 2))
print(calculator.divide(5, 0))

Output:

42
5.0
Cannot divide by zero!

2. Question: Create a package named shapes with two modules: circle.py and rectangle.py. In circle.py, write a function to calculate the area of a circle. In rectangle.py, write a function to calculate the area of a rectangle. Use these functions in another Python file.

Solution:

# shapes/circle.py

PI = 3.14159

def area(radius):
    return PI * (radius ** 2)

# shapes/rectangle.py

def area(length, width):
    return length * width

# main.py

from shapes import circle, rectangle

print(circle.area(5))
print(rectangle.area(4, 6))


Output:

78.53975
24

Summary

• Modules: Files containing Python code (functions, variables, classes).
• Packages: Folders containing multiple modules, organized with an __init__.py file.
• Benefits: Help organize, reuse, and maintain your code.

By using modules and packages, you can keep your code clean, organized, and easy to manage. Happy coding!