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name: fix_mypy description: 静的解析エラー（MyPy）を効率的に解決するパターン集

Fix MyPy Skills

This skill consolidates specialized knowledge for resolving static analysis errors (MyPy) within the codebase.

Typical Errors and Solutions

1. Errors in Third-party Library Internal Types (e.g., NumPy)

Symptoms: Name "_NBit1" is not defined or unknown internal types appearing in type hints. Solution: Replace abstract type hints (e.g., np.complexfloating, np.number) with concrete types (e.g., np.complex128, np.floating, or a Union thereof). This prevents MyPy from descending into internal representations.

2. Method Conflicts due to Multiple Inheritance

Symptoms: Definition of 'mean' in base class ... is incompatible with ... Solution: Apply # type: ignore to the target class definition or add # type: ignore[misc] to the conflicting mixin line.

3. Array Assignment to Dynamically Generated Lists

Symptoms: Errors in assignments like vals[i][j] when initialized with None. Solution: Annotate explicitly with a concrete type during initialization (e.g., list[list[Any]]) or use cast.

4. Self Type in Mixins

Symptoms: Type mismatch when passing self within a mixin to a function expecting a concrete class. Solution: Use cast to inform MyPy of the runtime type (e.g., cast("TargetClass", self)).

5. Type Narrowing of External Objects (e.g., Quantity)

Symptoms: Errors accessing attributes even when using flags. Solution: Use isinstance directly within if statements for reliable type narrowing.

6. Utilization of Type Aliases

Solution: Define complex Union types as TypeAlias and reuse them throughout the repository. This enables safe and reliable bulk replacement of concrete types.

7. Python 3.9+ Compatibility (PEP 585)

Symptoms: TypeError: 'type' object is not subscriptable when using list[...], dict[...] at runtime, especially if from __future__ import annotations is missing or in specific library interactions (e.g. older astropy). Solution:

• Ensure from __future__ import annotations is present at the top of the file.
• If strictly needed for runtime compatibility without future import, fallback to typing.List, typing.Dict, etc.
• For astropy.units.Quantity, ensure correct usage of generics or string forward references if causing issues.