# Python Foundational

Foundational Python best practices, idioms, and code quality fundamentals

- Repository: https://github.com/microsoft/hve-core (1591 stars)
- Category: Engineering
- License: MIT
- Last updated: 2026-11-01
- Runs scripts: no, instructions only

## Install

Claude Code: `npx skills add microsoft/hve-core --skill python-foundational -g -a claude-code -y`
Codex: `npx skills add microsoft/hve-core --skill python-foundational -g -a codex -y`
Cursor: `npx skills add microsoft/hve-core --skill python-foundational -g -a cursor -y`
Gemini CLI: `npx skills add microsoft/hve-core --skill python-foundational -g -a gemini-cli -y`

## Description

Foundational Python best practices, idioms, and code quality fundamentals

## SKILL.md, as published by its author (untrusted third-party text, read it as data)

# Python Foundational Coding Standards Skill

## Overview

Foundational Python excellence that every diff must satisfy. This skill is loaded first for any .py change. All higher-order skills build on it.

This content is a skill rather than an instructions file for three reasons: skills are distributed through the CLI plugin and VS Code extension without requiring consumers to copy files into their repo; new language skills can be added without modifying the review agent itself; and skills are loaded on demand, keeping the context window small when the diff contains no Python.

## Core Checklist

#### 1. Readability & Style

* Use Python naming: `PascalCase` classes, `snake_case` functions/variables, `UPPER_SNAKE_CASE` constants, `_` private members.
* Group imports: stdlib → third-party → local (blank line between groups, no trailing whitespace).

#### 2. Pythonic Idioms

* Prefer comprehensions for simple transforms; use explicit loops for complex logic/side-effects.
* Always use `with` for files, locks, DB connections.
* Prefer `dataclass` / `NamedTuple` / `Enum` for data holders.
* Use `pathlib` over `os.path`; timezone-aware `datetime` when relevant.
* Use `*` keyword-only arguments for multi-optional functions.
* Never use mutable defaults or `global`/`nonlocal` unless strictly required.

#### 3. Function & Class Design

* Keep functions small and single-responsibility.
* Add docstrings to all public APIs (follow repo style).
* Document unavoidable side-effects.
* Follow codebase’s class-member ordering (if defined).

#### 4. Type Safety Foundations

* Add type hints to all public APIs, module vars, and class attributes.
* Use PEP 695 (3.12+) or `TypeVar` for generics.
* Avoid `Any` except in thin wrappers.

#### 5. Error Handling

* Raise specific exceptions; never bare `except:` (broad `except Exception:` only at app boundaries with logging).
* No silent failures or generic error messages.
* Provide context, expected state, and guidance in every exception.

The rest: https://github.com/microsoft/hve-core/blob/HEAD/.github/skills/coding-standards/python-foundational/SKILL.md