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  • CEI rule in interviews — when do you actually break it without breaking the contract?

    ChainMentorNaina

    ChainMentorNaina

    @ChainMentorNaina
    Updated: Oct 28, 2025
    Views: 97

    Everyone tells juniors: “Follow Checks-Effects-Interactions.” ✅
    But the moment a Solidity interview goes deeper — we freeze. 😅

    Real world smart contract security isn’t just memorizing rules. Sometimes you do call external contracts early (maybe you need to verify a state on another protocol before changing your own storage). Other times, sticking blindly to CEI can even hurt functionality.

    What interviewers really want to see is your reasoning around re-entrancy risks, gas refunds, and how you structure interactions depending on trust boundaries.

    So I’m curious — have you hit a moment where CEI truly mattered in your code?
    When did you realize it’s a guideline, not a religion?

    5
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  • Abdil Hamid

    @ForensicBlockSmith • 3w

    I’ve seen junior developers move their state updates around just to match the “checks-effects-interactions” pattern and suddenly their contract invariants break 🤯.

    The real idea behind CEI is about trust. Only update your state when you’re sure the external call can’t interfere with it. Always think about re-entrancy risks, what a fallback function might do, and whether the contract you’re calling is trusted or upgradeable.

  • CryptoSagePriya

    @CryptoSagePriya • 3w

    That question “When would you break CEI?” is my interview nightmare too 😅. Then started giving like a threat model , umm something like What’s the risk? What’s the trade-off? How do I mitigate it if I call externally first? It shows you’re thinking like a smart contract engineer, not just reciting rules.

  • Abasi T

    @ggvVaSO • 3w

    I ignored CEI once and a malicious contract drained funds in tests. The shame taught me more than any tutorial ever did 😓. Learn from scars, not slogans.

  • FintechLee

    @FintechLee • 3w

    Communicating when you’re unsure is a critical signal. Interviewers want thought process: “Here’s the risk, here’s how I mitigate.” Clarity > bravado.

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