Fluent Python 2e example code

Example code for the book Fluent Python, Second Edition by Luciano Ramalho (O'Reilly, 2022).

Running the code with uv

This repository ships with a pyproject.toml and uv.lock so a single shared environment covers the example code across chapters. Python 3.12 is pinned via .python-version.

One-time setup

uv sync

That installs the runtime deps (click, fastapi, geolib, httpx, tqdm, uvicorn) plus the dev tools (pytest, mypy, ruff) into .venv/.

Running scripts

Use uv run — no need to activate the venv:

uv run python 19-concurrency/spinner_thread.py
uv run python 20-executors/demo_executor_map.py

Running doctests

pytest.ini is configured with --doctest-modules, so most chapter files double as doctests:

uv run pytest 11-pythonic-obj/vector2d_v0.py
uv run pytest 17-it-generator/sentence.py

Type-checking and linting

uv run mypy 11-pythonic-obj/vector2d_v0.py
uv run ruff check 11-pythonic-obj/

Caveats

• curio (used only in 21-async/domains/curio) is not in the shared env — its latest release is broken on Python 3.12. To run that example, create a separate environment with Python ≤3.11:

  cd 21-async/domains/curio && uv venv --python 3.11 && uv pip install curio

• A few chapters have their own requirements.txt from the upstream book repo. They overlap with the root environment and can generally be ignored.

Table of Contents

All chapters are undergoing review and updates, including significant rewrites in the chapters about concurrency in Part V.

New chapters in Fluent Python 2e are marked with 🆕.

🚨  This table of contents is subject to change at any time until the book goes to the printer.
Latest change: Old Part I—Prologue merged into new Part I—Data Structures; parts renumbered accordingly; chapter numbers unchanged.

Part / Chapter #	Title	Directory	1st ed. Chapter #
I – Data Structures
1	The Python Data Model	01-data-model	1
2	An Array of Sequences	02-array-seq	2
3	Dictionaries and Sets	03-dict-set	3
4	Unicode Text versus Bytes	04-text-byte	4
5	Data Class Builders	05-data-classes	🆕
6	Object References, Mutability, and Recycling	06-obj-ref	8
II – Functions as Objects
7	Funcions as First-Class Objects	07-1class-func	5
8	Type Hints in Functions	08-def-type-hints	🆕
9	Decorators and Closures	09-closure-deco	7
10	Design Patterns with First-Class Functions	10-dp-1class-func	6
III – Object-Oriented Idioms
11	A Pythonic Object	11-pythonic-obj	9
12	Special Methods for Sequences	12-seq-hacking	10
13	Interfaces, Protocols, and ABCs	13-protocl-abc	11
14	Inheritance: For Better or For Worse	14-inheritance	12
15	More About Type Hints	15-more-types	🆕
16	Operator Overloading	16-op-overloading	13
IV – Control Flow
17	Iterators, Generators, and Classic Coroutines	17-it-generator	14
18	with, match, and else Blocks	18-with-match	15
19	Concurrency Models in Python	19-concurrency	🆕
20	Concurrent Executors	20-executors	17
21	Asynchronous Programming	21-async	18
V – Metaprogramming
22	Dynamic Attributes and Properties	22-dyn-attr-prop	19
23	Attribute Descriptors	23-descriptor	20
24	Class Metaprogramming	24-class-metaprog	21