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Creating Custom Modules

  • Learn how to create your own Python modules to structure projects and reuse code efficiently.

  • What is a Custom Module?

    A custom module is a user-defined Python file (.py) that contains:

    • Functions

    • Variables

    • Classes

    Instead of writing the same code again and again, we reuse code by creating modules.

    Why Do We Create Custom Modules?

    • Code reusability

    • Better organization

    • Easy maintenance

    • Clean & readable programs

    • Professional project structure

    Creating a .py Module

    Any Python file can act as a module.

    Example File Structure:

    project/

    │

    ├── main.py

    └── calculator.py

    1.Creating a Custom Module

    Step 1: Create a Module File

    Create a file named calculator.py

Creating a Custom Module

This module contains basic arithmetic functions. 

# calculator.py

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

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

pi = 3.14

  • 2. Importing Custom Modules

    Method 1: Import Entire Module

    Syntax

    import module_name

Importing Entire Module

This program imports the full module and accesses its functions. 

# main.py
import calculator

print(calculator.add(10, 5))
print(calculator.pi)

  • Method 2: Import Specific Functions

    Syntax

    from module_name import function_name

Importing Specific Functions

This program imports only selected functions from the module. 

from calculator import add, subtract

print(add(8, 3))
print(subtract(10, 4))

  • Method 3: Import with Alias

    Syntax

    import module_name as alias

Using Alias for Module

This program imports module using a short name. 

import calculator as calc
print(calc.add(6, 2))

  • Method 4: Import Everything (Not Recommended)

    Syntax

    from module_name import *


Importing All Module Contents

Imports all functions and variables (may cause confusion). 

from calculator import *

print(add(4, 4))
print(pi)
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