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> If this is how std::optional worked, hardly anyone would use it. OK... Well, this is how kj::Maybe works and having written several hundred thousand lines of

• kllrnohj 5y ago
  Well, that seems to be using macros to cover up the syntax, which of course the C++ committee isn't going to recommend or use for anything new (nor should they). The actual implementation of Maybe doesn't seem to force anything, it just returns a pointer to the stored value. There's no enforcement of any kind that anything is checked as a result. There's some hoop-jumping with friend classes to "hide" the readMaybe() function to make the non-macro usage as ugly as possible to strongly encourage using the macro-convention, but that's hardly "enforcement". It's a cute syntax & macro pattern, but it's hardly a good fit for a C++ standard, either.
  • kentonv 5y ago
    The C++ committee could come up with actual syntax for this so it doesn't need macros. > There's no enforcement of any kind that anything is checked as a result. There's some hoop-jumping with friend classes to "hide" the readMaybe() function to make the non-macro usage as ugly as possible to strongly encourage using the macro-convention, but that's hardly "enforcement". Sure fine. Anyone who wants to reach into the internal APIs could also just as easily do `#define private public` and bypass every protection C++ has. We're not trying to defend against malicious developers here.