# Python Language

> Core Python 3.11+ language standards for typing, dataclasses, imports, pathlib, and stdlib-first code. Use for idiomatic language constructs in Python modules or stubs; defer pytest fixtures, database/client configuration, subprocess security, and other specialized concerns.

- Skill: `hoangnguyen0403/python-language` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add hoangnguyen0403/python-language`
- Raw SKILL.md: https://api.skillmd.com/api/skills/hoangnguyen0403/python-language/raw
- Safety review: PASS (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Security
- Author: HoangNguyen0403 (https://skillmd.com/u/hoangnguyen0403)
- Updated: 2026-08-19
- Page: https://skillmd.com/skills/hoangnguyen0403/python-language

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# Python Language

## **Priority: P0 (CRITICAL)**

## Rules

- Prefer `from __future__ import annotations` in modern modules.
- Type public functions, return values, and boundary data shapes.
- Use `pathlib.Path`, `contextlib`, `enum`, and stdlib helpers before custom wrappers.
- Use `@dataclass(frozen=True)` for immutable contracts and value objects.
- Prefer `Protocol`, `TypedDict`, or small dataclasses over `dict[str, Any]` sprawl.

## Recipe

1. **Model contracts explicitly** with dataclasses, typed dicts, or pydantic at I/O boundaries.
2. **Keep imports stable**: stdlib, third-party, local.
3. **Use comprehensions and generators carefully**; stop when readability drops.
4. **Choose explicit timezone-aware datetimes** for persisted or user-visible timestamps.
5. **Keep module side effects minimal**; import should not start work.

## Anti-Patterns

- **No mutable defaults**: use `field(default_factory=...)`.
- **No `os.path` in new code**: prefer `Path`.
- **No `Any` as escape hatch**: narrow unknown shapes or validate them.
- **No import-time env reads for volatile runtime state** unless cached config is intentional.

## Verify

- Run parser/type checks after cross-module type changes.
- Load [Framework Map](../references/framework-map.md) for category defaults.

## References

- [Framework Map](../references/framework-map.md)