The Expert's Guide to Python

For seasoned Pythonists, library authors, and performance‑minded engineers, this book goes far beyond idioms and into the mechanics that unlock real leverage. It distills hard‑won practices from modern CPython to help you write systems that are faster, safer, and easier to evolve-without sacrificing clarity. If you build frameworks, data pipelines, services, or tooling and want to exploit Python's lesser‑known capabilities with confidence, this guide is your map to the terrain professionals actually traverse.

You'll dissect the runtime-subinterpreters and the per‑interpreter GIL, immortal objects, adaptive specialization, and vectorcall-then harness the modern typing core: parameterized aliases and type parameters (PEP 695), protocols (PEP 544), Self (PEP 673), variadic generics (PEP 646), and override checks (PEP 698). You'll master structural pattern matching for robust dispatch; exploit descriptors, __slots__, and metaclasses for high‑performance, declarative object models; and architect asynchronous systems with precise task/cancellation semantics, context variables, async resource management, TaskGroup‑based structured concurrency, and ExceptionGroup/except*. You'll turn the import system into a platform for plugins, use pyproject.toml and contemporary backends to ship reproducible wheels, and apply power patterns-single‑dispatch and PEP 701 f‑strings-for expressive, introspection‑friendly APIs.

Prerequisites: strong Python experience and familiarity with asyncio and type hints. The book favors verifiable techniques-type‑checked, benchmarked, and tool‑friendly-pairing deep explanations with pragmatic checklists, failure modes, and migration advice for real codebases.