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Comment by ijustlovemath | Hacker News Reader

static variable addresses are an extremely important tool in static analysis, for proving certain program invariants hold. In C, a const static often will be able to tell you more about the structure of your code at runtime than a #define macro ever could!

though unless you're programming extremely defensively (eg trying to thwart a nation state), I see no reason why you would use them at runtime

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Could you expand on this? I don't understand the point you're making, or how it's useful.

static consts in C carry their identity through their (fixed, unchanging) pointer address. Lets say you have a business rules engine, that's only meant to ingest threshold values from a certain module. You want to know if the 3.0 you're using is coming from the correct place in the code, or if there's a programming error. With a define, there's not enough additional information to be able to. With a static const, you can just have a const static array of pointers to the valid threshold constants, and use that in your tests for the rules engine.

I work in a highly regulated field, so often this level of paranoia and proof helps us make our case that our product works exactly the way we say it works.

So it's easier to guarantee the identity is correct? That doesn't stop you from using the incorrect identity, though.

I'm not quite sure I understand how this is better than a define - if you know enough to know whether you're using the correct value, it can just as easily be a define?

I think I can see the idea, but I'm probably not paranoid enough to understand how it's helpful XD

Perhaps a distinction between static analysis (at compile) and dynamic analysis (at run time) is useful ?

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