Python

Python is a widely used high-level, general-purpose, interpreted, dynamic programming language.

Language deep dives

• Decorators - wrapping callables (with functools.wraps, arguments, stacking, and the kinds of decorators).
• Descriptors - the __get__/__set__ protocol behind properties, methods and ORM fields.

Web frameworks

• Python Web Frameworks - the field compared: Django, FastAPI, Flask, Litestar, Starlette.
• Django - the batteries-included framework: query and migration cookbook, ORM gotchas, async limits (see also Django authentication).
• FastAPI and Starlette - the async, type-hinted stack (FastAPI builds on Starlette).
• aiohttp - async HTTP client and server, the non-ASGI branch of the async world.
• Jinja2 - templating: undefined values, whitespace, macros, and the defaults that bite.
• WTForms - form handling and validation (a legacy choice today).

Data and libraries

• Pandas - data wrangling, and the defaults that quietly change a result.
• Jupyter - notebooks: running them from the command line, kernels, hidden state.
• SQLAlchemy - SQL toolkit and ORM (see also Databases).
• Odoo - the ERP framework.
• Bonobo - ETL toolkit (not maintained for now).

Testing

• Testing with Python - pytest in practice: project layout, fixtures, parametrization, mocking, coverage, and the collection gotchas that pass in silence.

Cookbook

Compute the directory of the current file:

from pathlib import Path

HERE = Path(__file__).resolve().parent

Older recipes join __file__ to os.getcwd() first. That was for the script run from the command line, whose __file__ used to be relative: since Python 3.9 it is absolute too, so the join is a no-op (checked on 3.15, from two different working directories). resolve() is still worth keeping, it follows symlinks.

Links and references

• OrderedDict subclass implementing insertion methods to adjust the order