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Appendix: Book Notes#

Resources and Ideas for eventual inclusion in the book.

  • Walrus operator?
  • reveal_type/assert_type

AI-Generated Topic List#

Created by ChatGPT 4o.

📘 Part I: The Basics of Typing in Python#

Introduction to Static Typing#

  • Why type your code?
  • Benefits of types in Python (readability, tooling, correctness)

Basic Type Annotations#

  • Built-in types: int, str, float, bool
  • Variable annotations
  • Function argument and return types

Optional and Union Types#

  • Optional[T] / T | None
  • Union / T1 | T2
  • When and why to use

Any and NoReturn#

  • When to use Any
  • Risks of Any
  • Meaning and use of NoReturn

Type Aliases#

  • Creating and using type MyAlias = ...
  • Organizing complex types

📘 Part II: Collections and Generics#

Typing Built-in Collections#

  • List, Dict, Tuple, Set
  • Homogeneous vs heterogeneous types
  • Variadic tuples

Generic Types#

  • Understanding type variable and generic functions
  • Creating generic classes

Callable and Lambdas#

  • Typing functions as values
  • Callable signatures

Iterables and Iterators#

  • Iterable, Iterator, Generator
  • Typing generators and coroutines

Literal Types#

  • Restricting to fixed string or numeric values
  • Using Literal for flags and enums

📘 Part III: Advanced Concepts#

Protocols and Structural Typing#

  • Introduction to duck typing
  • Protocol classes and @runtime_checkable

New in Python 10+#

  • | syntax for unions
  • match statement and typing with pattern matching

Annotated and Metadata Types#

  • Using Annotated for richer metadata
  • Use in CLI tools, validation, etc.

Self Type and Recursive Types#

  • Typing methods that return self
  • Recursive types like nested JSON

Dataclasses and Typing#

  • Typing fields with and without defaults
  • InitVar, field, kw_only, etc.

📘 Part IV: Runtime Typing and Validation#

Type Checking at Runtime#

  • isinstance and typing.get_type_hints()
  • Runtime enforcement libraries (e.g. Pydantic, Enforce)

Validating with Decorators#

  • Type validation decorators
  • Enforcing types in dynamic code

TypedDict and JSON-like Structures#

  • Using TypedDict for structured data
  • Migration from dict[str, Any]

Enums and Custom Types#

  • Strongly typed enums
  • Creating domain-specific types

Dynamic Typing Interop#

  • Working with untyped or partially typed code
  • Handling Any gracefully

📘 Part V: Tooling and Practices#

Static Type Checkers#

  • Using mypy, pyright, Pyrefly,pytype`
  • Configuration and workflows

IDE and Editor Support#

  • VS Code, PyCharm, etc.
  • Type hinting with LSPs and plugins

Refactoring with Types#

  • Incremental typing strategies
  • Using types to guide refactoring

Testing and Typing#

  • Typing test code
  • Type-aware mocking and fixtures

Types in Documentation#

  • Sphinx and autodoc with type annotations
  • Docstrings vs annotations

📘 Part VI: Real-World Applications#

Typing APIs and Libraries#

  • Public API surfaces
  • Library development with types

Using Types in Frameworks#

  • Django/Pydantic/FastAPI with typing
  • Typing decorators and middleware

Typing Concurrency#

  • async def, Awaitable, Coroutine
  • Thread, Process, Queue

Cross-Version Compatibility#

  • Using typing_extensions
  • Supporting older Python versions

Common Pitfalls and Anti-Patterns#

  • Misusing Any
  • Over-annotating
  • Annotations that hinder readability