Python type safety with type hints, generics, protocols, and strict type checking. Use when adding type annotations, implementing generic classes, defining structural interfaces, or configuring mypy/pyright.
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Python type safety with type hints, generics, protocols, and strict type checking. Use when adding type annotations, implementing generic classes, defining structural interfaces, or configuring mypy/pyright.
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Stars38,174
Forks4,092
LanguagePython
LicenseMIT
📦 Ships with wshobson-agents
</> SKILL.md
python-type-safety.SKILL.md
---name: python-type-safety
description: Python type safety with type hints, generics, protocols, and strict type checking. Use when adding type annotations, implementing generic classes, defining structural interfaces, or configuring mypy/pyright.
---# Python Type Safety
Leverage Python's type system to catch errors at static analysis time. Type annotations serve as enforced documentation that tooling validates automatically.
## When to Use This Skill
- Adding type hints to existing code
- Creating generic, reusable classes
- Defining structural interfaces with protocols
- Configuring mypy or pyright for strict checking
- Understanding type narrowing and guards
- Building type-safe APIs and libraries
## Core Concepts
### 1. Type Annotations
Declare expected types for function parameters, return values, and variables.
### 2. Generics
Write reusable code that preserves type information across different types.
### 3. Protocols
Define structural interfaces without inheritance (duck typing with type safety).
### 4. Type Narrowing
Use guards and conditionals to narrow types within code blocks.
Detailed sections (starting with `## Advanced Patterns`) live in `references/details.md`. Read that file when the navigation summary above is insufficient.
## Best Practices Summary
1. **Annotate all public APIs** - Functions, methods, class attributes
2. **Use `T | None`** - Modern union syntax over `Optional[T]`
3. **Run strict type checking** - `mypy --strict` in CI
4. **Use generics** - Preserve type info in reusable code
5. **Define protocols** - Structural typing for interfaces
6. **Narrow types** - Use guards to help the type checker
7. **Bound type vars** - Restrict generics to meaningful types
8. **Create type aliases** - Meaningful names for complex types
9. **Minimize `Any`** - Use specific types or generics. `Any` is acceptable for truly dynamic data or when interfacing with untyped third-party code
10. **Document with types** - Types are enforceable documentation
