alt Hacker NewsC's lack of all of
- sum/union types
- multiple return values/tuple types
- exceptions
means that most ways of returning an error from a function are not available in C. Because of this, many C APIs, including `crypt` in this case, resort to in-band error signalling by using a sentinel value (like NULL, a negative integer, "*" etc.).
Most other languages lack one or two of the above, but very few lack all three, and so most have developed a different culture around error reporting (Result in Rust, multiple return values in Go, exceptions in Java, Python etc.).
Replies
jppittma • today at 2:29 PM
C has sum types/unions? What are you talking about? You don't need multiple return. You can use a struct and it's the same thing.
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One of the small but important significances of Rust is that it very often gets to have the same machine code as a correct "in-band error signalling" strategy from C but with source code that the maintainers can actually understand.
And really often when your "in-band error signalling" in Rust is more expensive you realise (perhaps to your horror) that your C wouldn't be correct, so you just dodged a bullet. For example Option<OwnedFd> is, like OwnedFd, a 32-bit value, Unix has always reserved -1 to mean invalid, so Rust can treat that as a niche. But the Windows equivalent Option<OwnedHandle> can't do this because, well, cue Raymond Chen: https://devblogs.microsoft.com/oldnewthing/20040302-00/?p=40...