grandempire a day ago

No. This is how sum types are implemented.

And from a runtime perspective it’s going to be a struct with perhaps more padding. You’ll need more details about your specific threat model to explain why that’s bad.

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  • mistrial9 a day ago

    a quick search says that std::variant is the modern replacement to implement your niche feature "sum types"

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    • jlouis a day ago

      Not a niche feature. Fundamental for any decent language with a type system.

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      • mistrial9 19 hours ago

        ok, but C99 and C++11 and others, all have ways to implement types. "Fundemental" as you say.. using UNION in C++ is not a good choice to implement types.. in old C99, you can use UNION that way but why? footguns all around.

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    • soraminazuki a day ago

      Whoa, that's a core building block of programming and computer science that you're dismissing as "niche" without explanation.

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      • mistrial9 19 hours ago

        yes types are a core building block of programming and computer science, but not using UNION ? this casual dismissal of "criticisms of UNION" here seems superficial and un-wise to me.

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        • soraminazuki 15 hours ago

          Sum types, not C unions. Different concepts.

          A sum type is a concept from type theory. Like unions, it expresses a type that can be either one of multiple types. But unlike unions, it retains information about which type it is.

          Properly implemented sum types are completely type safe. I can't be 100% sure what your particular "criticisms" of C unions precisely are, but assuming they all relate to type safety, they don't apply to sum types.

          Sum types are important because any real world project has to deal with data that's either A or B. There's nothing controversial here.

          In C, a union is a way to implement that. Yes, it's unsafe. But can you eliminate the use of unsafe features from C projects? No, if they deal with memory.

          Also, it's rich and quite frankly rude to brush off my comment as "casual dismissals," "superficial," and "unwise" when it's a direct response to this.

          > your niche feature "sum types"

          That's pure unprovoked smugness right there that contains no substance of what your criticisms actually are, let alone the reason.

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