python-expert-best-practices-code-review
Python best practices for writing production-grade code. This skill should be used when writing, reviewing, or refactoring Python code. Triggers on tasks involving Python development, error handling patterns, dictionary operations, and code quality improvements.
What this skill does
# Python 3.14+ Expert Best Practices Simple, pragmatic, opinionated. Only what matters for writing production-grade python code. ## When to Apply Reference these guidelines when: - Writing Python functions, classes, or modules - Reviewing Python code for error handling issues - Refactoring existing Python codebases - Implementing data validation and API boundaries - Optimizing error detection and debugging patterns ## Rule Categories by Priority | Priority | Category | Impact | Prefix | |----------|----------|--------|--------| | 1 | Error Handling | CRITICAL | `dict-`, `operators-` | | 2 | Common Bugs | CRITICAL-HIGH | `no-mutable-`, `no-generic-` | | 3 | Code Clarity | HIGH-MEDIUM | `listcomp-`, `no-inline-` | | 4 | Code Style | LOW | `avoid-`, `unnecessary-` | ## Quick Reference - `dict-required-keys` - Use `d[key]` for required dictionary keys to fail fast with KeyError - `no-mutable-defaults` - No mutable defaults in function/method parameters - `operators-return-notimplemented` - Return NotImplemented for unsupported operand types and design + vs += intentionally - `no-generic-except` - Avoid generic except clauses to prevent hiding unexpected errors - `listcomp-no-side-effects` - List comprehensions must produce a value you use (no side-effect listcomps) - `no-inline-imports` - Place all import statements at the top of the file - `avoid-explanatory-comments` - Avoid unnecessary comments for self-documenting code - `unnecessary-else-blocks` - Avoid unnecessary else blocks after return/break/continue statements ## How to Use Read individual rule files for detailed explanations and code examples: ``` rules/dict-required-keys.md rules/no-mutable-defaults.md rules/operators-return-notimplemented.md rules/no-generic-except.md rules/listcomp-no-side-effects.md rules/no-inline-imports.md rules/avoid-explanatory-comments.md rules/unnecessary-else-blocks.md ``` Each rule file contains: - Brief explanation of why it matters - When to use and when not to use the pattern - Implementation requirements - Incorrect code example with explanation - Correct code example with explanation - Additional context and references
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