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Use when building Python 3.11+ applications requiring type safety, async programming, or robust error handling. Generates type-annotated Python code, configures mypy in strict mode, writes pytest test
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Paste the copied command in a terminal. It installs this SKILL.md into that agent.
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Use when building Python 3.11+ applications requiring type safety, async programming, or robust error handling. Generates type-annotated Python code, configures mypy in strict mode, writes pytest test suites with fixtures and mocking, and validates code with black and ruff. Invoke for type hints, async/await patterns, dataclasses, dependency injection, logging configuration, and structured error handling.
Use when building Python 3.11+ applications requiring type safety, async programming, or robust error handling. Generates type-annotated Python code, configures mypy in strict mode, writes pytest test suites with fixtures and mocking, and validates code with black and ruff. Invoke for type hints, async/await patterns, dataclasses, dependency injection, logging configuration, and structured error handling.
Modern Python 3.11+ specialist focused on type-safe, async-first, production-ready code.
mypy --strict, black, ruff
Load detailed guidance based on context:
| Topic | Reference | Load When |
|---|---|---|
| Type System | references/type-system.md | Type hints, mypy, generics, Protocol |
| Async Patterns | references/async-patterns.md | async/await, asyncio, task groups |
| Standard Library | references/standard-library.md | pathlib, dataclasses, functools, itertools |
| Testing | references/testing.md | pytest, fixtures, mocking, parametrize |
| Packaging | references/packaging.md | poetry, pip, pyproject.toml, distribution |
X | None instead of Optional[X] (Python 3.10+)from pathlib import Path
def read_config(path: Path) -> dict[str, str]:
"""Read configuration from a file.
Args:
path: Path to the configuration file.
Returns:
Parsed key-value configuration entries.
Raises:
FileNotFoundError: If the config file does not exist.
ValueError: If a line cannot be parsed.
"""
config: dict[str, str] = {}
with path.open() as f:
for line in f:
key, _, value = line.partition("=")
if not key.strip():
raise ValueError(f"Invalid config line: {line!r}")
config[key.strip()] = value.strip()
return config
from dataclasses import dataclass, field
@dataclass
class AppConfig:
host: str
port: int
debug: bool = False
allowed_origins: list[str] = field(default_factory=list)
def __post_init__(self) -> None:
if not (1 <= self.port <= 65535):
raise ValueError(f"Invalid port: {self.port}")
import asyncio
import httpx
async def fetch_all(urls: list[str]) -> list[bytes]:
"""Fetch multiple URLs concurrently."""
async with httpx.AsyncClient() as client:
tasks = [client.get(url) for url in urls]
responses = await asyncio.gather(*tasks)
return [r.content for r in responses]
import pytest
from pathlib import Path
@pytest.fixture
def config_file(tmp_path: Path) -> Path:
cfg = tmp_path / "config.txt"
cfg.write_text("host=localhost\nport=8080\n")
return cfg
@pytest.mark.parametrize("port,valid", [(8080, True), (0, False), (99999, False)])
def test_app_config_port_validation(port: int, valid: bool) -> None:
if valid:
AppConfig(host="localhost", port=port)
else:
with pytest.raises(ValueError):
AppConfig(host="localhost", port=port)
[tool.mypy]
python_version = "3.11"
strict = true
warn_return_any = true
warn_unused_configs = true
disallow_untyped_defs = true
Clean mypy --strict output looks like:
Success: no issues found in 12 source files
Any reported error (e.g., error: Function is missing a return type annotation) must be resolved before the implementation is considered complete.
When implementing Python features, provide:
Python 3.11+, typing module, mypy, pytest, black, ruff, dataclasses, async/await, asyncio, pathlib, functools, itertools, Poetry, Pydantic, contextlib, collections.abc, Protocol
Maintained by @jeffallan, Principal Consultant at Synergetic Solutions