Python 3 Deep Dive

Notes from the Python 3 Deep Dive series (Udemy). Python is a “batteries-included” language — a large standard library and a culture of readability.

Course

The Zen of Python

import this

Beautiful is better than ugly.
Explicit is better than implicit.
Simple is better than complex.
Complex is better than complicated.
Flat is better than nested.
Sparse is better than dense.
Readability counts.

(Tim Peters — PEP 20.)

PEPs

Python Enhancement Proposals document proposed and accepted language features. PEP 8 (style) and PEP 20 (Zen) are the ones you’ll cite most.

Mental Model Highlights

• Everything is an object — including functions and classes; names are references bound to objects.
• Mutable vs immutable — list/dict/set mutable; int/str/tuple immutable. Drives copying, default-arg, and hashing gotchas.
• Truthiness — empty containers, 0, None, "" are falsy.
• is vs == — identity vs equality; use is only for None/singletons.

Modern Tooling

uv venv && source .venv/bin/activate   # fast venv + installs (uv)
ruff check . && ruff format .          # lint + format
python -m pytest                       # tests