Python

name: Python slug: python version: 1.0.1 description: Write reliable Python avoiding mutable defaults, import traps, and common runtime surprises. metadata: {"clawdbot":{"emoji":"🐍","requires":{"bins":["python3"]},"os":["linux","darwin","win32"]}}

Quick Reference

Critical Rules

小葱技能7w4.net持续更新中。

• def f(items=[]) shares list across all calls — use items=None then items = items or []
• is checks identity, == checks equality — "a" * 100 is "a" * 100 may be False
• Modifying list while iterating skips elements — iterate over copy: for x in list(items):
• GIL prevents true parallel Python threads — use multiprocessing for CPU-bound
• Bare except: catches SystemExit and KeyboardInterrupt — use except Exception:
• UnboundLocalError when assigning to outer scope variable — use nonlocal or global
• open() without context manager leaks handles — always use with open():
• Circular imports fail silently or partially — import inside function to break cycle
• 0.1 + 0.2 != 0.3 — floating point, use decimal.Decimal for money
• Generator exhausted after one iteration — can't reuse, recreate or use itertools.tee
• Class attributes with mutables shared across instances — define in __init__ instead
• __init__ is not constructor — __new__ creates instance, __init__ initializes
• Default encoding is platform-dependent — always specify encoding='utf-8'

这是一份专注于 Python 常见陷阱的实用速查包，涵盖类型、函数、并发、测试等多个方面，结构清晰、分类明确，适合快速查阅和避坑。优点是内容精炼、针对性强，Critical Rules 设计便于快速定位关键问题；不足之处在于部分主题讲解较浅，缺少代码示例和场景化指引，整体更像是错误清单而非全面的实践指南。基础避坑够用，但深度和系统性有提升空间。