v1.0.0 Stable Release

Professional Calculator

A fully-featured desktop calculator with a hand-written expression engine.

⚡ Note: This was built in month 5 of my self-taught journey (May 2026).

~ About the Project

Unlike a simple GUI wrapper around eval(), this application ships with a completely hand-written expression engine: a tokenizer, a shunting-yard parser, and a Decimal-precision evaluator. It is paired with a polished, Casio-inspired interface built using NiceGUI.

This project represents a massive step up in engineering discipline. It features a modular architecture, a strict quality pipeline (black, isort, flake8, mypy, bandit), and a comprehensive suite of 91 passing unit tests covering all layers.

~ Tech Stack & Architecture

Python 3.12 NiceGUI Decimal Precision Shunting-Yard Parser pytest (91 tests) PyInstaller

~ How to Run

Option 1: Standalone Executable

Download the .exe from the GitHub Releases page. No Python installation or terminal is required. Just double-click to run.

Option 2: From Source

1. Clone the repository and install dependencies:

git clone https://github.com/Tharana-Dev/Professional-Calculator.git
cd Professional-Calculator
pip install -r requirements.txt

2. Run the GUI (Windows CMD):

set PYTHONPATH=src && python -m calculator.gui

Or if you are using PowerShell:

$env:PYTHONPATH="src"; python -m calculator.gui

3. Run the 91 unit tests:

pytest tests/

~ Want to try it?

Download the source code or the standalone executable, and let me know what you think of the interface and the custom math engine!

Download Source ⬇ Email ideas →