try · except · else · finally — Python errors | L07 · Advanced
Python error handling the senior way. Beginners catch every error or none. Seniors know which to catch, where, and what to do once caught.
You'll learn:
• try / except / else / finally — the 4-block discipline (most beginners use 2)
• 6 builtin exceptions you'll catch weekly (ValueError, KeyError, FileNotFoundError, etc.)
• Custom exceptions — class PaymentFailed(Exception) — domain-specific signals
• Defensive vs Paranoid coding — when NOT to catch (the bug hiding pattern)
• raise ... from e — preserve traceback context (the senior reflex)
The judgment call:
• `except Exception: pass` is THE Python anti-pattern (we'll cover why)
• EAFP - LBYL — Easier to Ask Forgiveness than Permission
• Mock the boundary, not the unit — applies to error handling too
→ Error handling reference: https://dargslan.com
→ Next: L08 Files + JSON — pathlib, with, json.load
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