For context: I am trying to write a Rust wrapper over a C library.

Like many C libraries, most of its functions return an int. Positive return values are meaningful (provides information) and negative values are error codes.

To give an example, think of something like int get_items_from_record(const struct record *rec, struct item *items). A positive value indicates how many items were returned. -1 could mean ErrorA, -2 ErrorB, and so on.

Since this is Rust, I want to represent this kind of integer as Result<T, E>, e.g.:

enum LibError {
    A = -1,
    B = -2,
    // ....
}

// LibResult is ideally just represented as an integer.
type LibResult = Result<NonNegativeInteger, LibError>;

// Then I can pass LibResult values back to the C code as i32 trivially.

Is there a way/crate to do this?

  • hansl@lemmy.world
    6·
    1 year ago

    I think you can implement Into for Result<…, LibError>. You can also implement the branching trait of Result so ? works. I’ve done it for booleans in the past as a learning experiment.

    Unfortunately on mobile so I can’t link or copy paste code but that should give you some pointers to the right doc.