Refactoring · interview question

What is the healthiest performance judgment around types during refactors?

Multiple choiceHardchapter-10-curatedpremiumrefactoringtypes-during-refactors

python

def build_receipt(order_id: str, subtotal: float, shipping: float) -> str:
    return f"{order_id}:{subtotal + shipping:.2f}"

Measure before optimizing, then change the part that actually dominates cost instead of guessing from style alone.Solve the symptom with comments only and avoid changing the code shape around types during refactors.Delay clarity until production traffic reveals the edge case and then patch it under pressure.Keep types during refactors implicit so the script stays short and hope the next engineer infers the rule.

Answer and explanation

Correct answer

A. Measure before optimizing, then change the part that actually dominates cost instead of guessing from style alone.

Why

Premature optimization is usually weaker than targeted optimization backed by measurement.

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What is the healthiest performance judgment around types during refactors?

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