Python Interview Questions · interview question

Which practice avoids a common mistake with Mutable Default Arguments?

Multiple choiceMediumpython-interview-2026interviewpythonpitfall

Silence the Mutable Default Arguments problem by using broad catches, hidden globals, or extra shared mutable state.Ignore the Mutable Default Arguments issue and rely on team discipline instead of clearer APIs or invariants.Do not use a mutable default when you expect a brand-new container every call, because the same object will be reused.Prefer the version of Mutable Default Arguments that makes behavior less predictable as long as the code still runs.

Answer and explanation

Correct answer

C. Do not use a mutable default when you expect a brand-new container every call, because the same object will be reused.

Why

Do not use a mutable default when you expect a brand-new container every call, because the same object will be reused. This is a common failure mode in real Python code and a frequent interview follow-up.

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Which practice avoids a common mistake with Mutable Default Arguments?

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