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Since C++17 there is std::variant https://en.cppreference.com/w/cpp/utility/variant.html https://en.cppreference.com/w/cpp/utility/variant.html

• maleldil 8mo ago
  These are not proper sum types, since you're limited to one variant per type.
  • sebtron 8mo ago
    I am not sure what you mean, you can definitely have e.g. an std::variant<int, std::string, bool> Which is a sum of those three types.
    • maleldil 8mo ago
      See the first IpAddr example here[1], where you have separate variants, both with string representations. You can't do this with std::variant. You have to use separate types. [1] https://doc.rust-lang.org/book/ch06-01-defining-an-enum.html https://doc.rust-lang.org/book/ch06-01-defining-an-enum.html
      • sebtron 8mo ago
        I see what you mean now, thanks. To reproduce that example with std::variant I would need some kind of strong type alias, which as far as I know is missing from C++; so the only feasible way to do that would be wrapping the string in another class or struct.