Running Python

python <filename>

Installing Packages with PIP

pip install flask

• If you don’t use a virtual environment, packages are installed into the global site-packages directory, which affects all projects.
• If you use a virtual environment (venv), packages are installed only inside that environment, keeping dependencies isolated.

.venv\\Scripts\\activate   # Windows
source .venv/bin/activate  # macOS/Linux

Dependency Management

Instead of manually installing packages, you can record dependencies so others can easily set up the same environment:

pip install -r requirements.txt   # traditional way

# Modern tools like uv support pyproject.toml and lock files:
uv sync          # install dependencies from pyproject.toml and uv.lock
uv add requests  # add a dependency

uv

# 1) Initialize a new project (creates pyproject.toml)
uv init flask-demo
cd flask-demo

# 2) Create a virtual environment (optional, uv run will auto-use it)
uv venv

# 3) Add dependencies (updates pyproject.toml + uv.lock)
uv add flask python-dotenv

# 4) Create a minimal Flask app
ni app.py -Value @"
from flask import Flask
app = Flask(__name__)

@app.get('/')
def home():
    return {'msg': 'Hello, Flask + uv!'}

if __name__ == '__main__':
    app.run(debug=True)
"@

# 5) Run (automatically uses the venv)
uv run python app.py
uv run flask --app run:app run --debug

Deployment

uv add gunicorn
uv run gunicorn -w 4 -b 0.0.0.0:8000 app:app