Python Practice

Master the data model, generators, decorators, and asyncio.

Language Essentials

Concept	Details
Memory Model	Reference counting + cycle GC, everything is an object, __slots__
Type System	Dynamic, gradual typing (typing module), protocols, TypeVar
Error Handling	Exceptions (try/except/else/finally), ExceptionGroup (3.11+)
Concurrency	asyncio, threading (GIL), multiprocessing, free-threading (3.13+)
Build	uv, pip, pyproject.toml, ruff for linting
Standard	CPython 3.12+

Key Idioms

• Dunder methods (__init__, __repr__, __iter__) for protocol conformance
• Generators and yield from for lazy sequences
• Decorators (function and class) for cross-cutting concerns
• Context managers (with statement, __enter__/__exit__)
• Comprehensions (list, dict, set, generator) over explicit loops
• dataclasses and attrs for structured data
• Descriptors for attribute access control
• match statement (3.10+) for structural pattern matching

Reference Documentation

• Python docs — authoritative
• Data Model reference — essential
• Fluent Python (Ramalho, 2nd ed.) — deep Pythonic patterns
• Python Cookbook (Beazley & Jones) — recipes
• Real Python — tutorials

Practising these

practice/bin/ol list  build python          # which of these have references yet
practice/bin/ol start build python 01       # clone it stubbed into .scratchpad/
practice/bin/ol check build python 01       # run it; exit code is the verdict
practice/bin/ol diff  build python 01       # your attempt against the reference

Exercises are ordered by concept, not by difficulty, so pick by the stars rather than by the number. An exercise listed below with no reference yet is a row in this table and nothing more; see the practice path for how the harness works.

Exercises

#	Exercise	Concepts	Difficulty
01	Descriptor-based ORM	Descriptors, metaclasses, __set_name__	⭐⭐⭐⭐
02	Async task scheduler	asyncio, event loop, Future, cancellation; course version: lang.08, data.01	⭐⭐⭐
03	Generator-based pipeline	yield, send, throw, coroutine chaining; course version: data.02	⭐⭐⭐
04	Property-based test framework	Decorators, inspect, random generation, shrinking; course version: craft.04	⭐⭐⭐⭐
05	LRU cache with TTL	__hash__, __eq__, doubly-linked list, threading.Lock; course version: gw.06	⭐⭐⭐
06	Import hook (custom loader)	importlib, sys.meta_path, ModuleSpec	⭐⭐⭐⭐⭐
07	Dataclass code generator	ast module, metaprogramming, exec	⭐⭐⭐⭐
08	Actor model (multiprocessing)	multiprocessing.Queue, Process, message passing; course version: data.04	⭐⭐⭐
09	Type checker (subset)	typing, AST walking, unification algorithm	⭐⭐⭐⭐⭐
10	WSGI framework (mini-Flask)	WSGI spec, decorators, routing, middleware	⭐⭐⭐