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John Carmack on mutable variables

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498 points azhenley | 1 comments | 31 Oct 25 02:34 UTC | HN request time: 0.21s | source
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zahlman ◴[31 Oct 25 15:22 UTC] No.45773060[source]▶
> and it avoids problems where you move a block of code and it silently uses a version of the variable that wasn’t what it originally had.

I find that keeping functions short also helps a ton with that.

No, shorter than that. Short enough that the only meaningful place to "move a block of code" is into another function. Often, by itself.

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williamdclt ◴[31 Oct 25 15:27 UTC] No.45773136[source]▶
It helps with that, but it has other trade-offs: indirection isn't free for readability.
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1. tengbretson ◴[31 Oct 25 15:51 UTC] No.45773451[source]▶
> indirection isn't free for readability

Yes, but also no. If its a mostly side-effect free function with a good name and well defined input/output types its basically free.