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Python Exception Gotchas: raise from, finally Overriding return, Lost Variables, Exception vs BaseException

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Self-Hosting & Infra intermediate 6 min read $0.01 Updated 2026-10-20

Executed on Python 3.10: implicit context versus explicit cause versus from None, finally ordering and return override, continue inside try, bare raise error, KeyboardInterrupt, except-as variable deletion, custom exception args, and assert under -O.

Wrap errors without losing the original cause, understand why return in finally swallows exceptions, why the caught variable disappears, why bare raise fails outside a handler, and what except Exception does not catch.

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#python#exceptions#error-handling#debugging#gotchas

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