0159-python-type-safety

What problem does it solve?

It helps you prevent bugs caused by incorrect values, mismatched interfaces, and missing null/union handling by enforcing Python type checking during static analysis.

Core Features & Use Cases

• Type-safe public APIs: Annotate function signatures, methods, and class interfaces so tools can validate correct usage.
• Generics, Protocols, and type narrowing: Preserve type information across reusable components using Generic, define structural interfaces with Protocol, and narrow T | None safely with guards.
• Strict type checking configuration: Use mypy --strict or Pyright with strict rules to surface issues early in CI rather than at runtime.
• Use Case: When building an internal library or service layer, define repository interfaces and response types so consumers cannot accidentally call methods with the wrong entity type or forget to handle missing results.

Quick Start

Configure your project to run strict mypy or pyright and add type annotations to your public functions, then validate that nullable return types like User | None are handled explicitly.