Today Learn Simple Python Package to create a Simple Invoice Function

 

What is a Python Package?

A Python package is a way of organizing related Python code into a structured collection of modules. Instead of putting all the functions into one large Python file, we can separate them into smaller files according to their purpose.

For example, in our simple accounting project, we create an accounting package containing functions for calculating an invoice.

InvoiceProject/
│
├── accounting/              ← Python package
│   ├── __init__.py          ← Package entry point
│   ├── invoice.py           ← Invoice calculations
│   ├── tax.py               ← Tax calculation
│   └── total.py             ← Total calculation
│
├── invoice_report.py        ← Combines the calculations
│
└── invoice_demo.ipynb       ← Jupyter Notebook

The advantage is that each module has a specific responsibility, making the code easier to understand, maintain, reuse, and expand.

How the package works

The architecture of our invoice application can be illustrated as follows:

                 User Input
              Quantity / Price
                 Tax Rate
                     │
                     ▼
            ┌─────────────────┐
            │ invoice_report  │
            │     .py         │
            └────────┬────────┘
                     │
                     ▼
            ┌─────────────────┐
            │   accounting    │
            │     package     │
            └────────┬────────┘
                     │
          ┌──────────┼──────────┐
          ▼          ▼          ▼
     ┌─────────┐ ┌─────────┐ ┌─────────┐
     │invoice  │ │   tax   │ │  total  │
     │  .py    │ │   .py   │ │   .py   │
     └────┬────┘ └────┬────┘ └────┬────┘
          │           │           │
          ▼           ▼           ▼
       Subtotal       Tax        Total
          │           │           │
          └───────────┼───────────┘
                      ▼
             ┌─────────────────┐
             │ Jupyter Notebook│
             └────────┬────────┘
                      ▼
                Invoice Report

In simple terms

Think of a Python package like an accounting department in a company.

• invoice.py → handles invoice calculations
• tax.py → handles tax calculations
• total.py → calculates the final amount
• __init__.py → connects the modules and makes them available as a package
• invoice_report.py → coordinates the calculations
• Jupyter Notebook → presents the final result

This approach allows us to break a large program into smaller, manageable components, while each component can be reused in other programs.

In short: A Python package is a structured way to organize and reuse related Python modules and functions.