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?
I think you can implement Into<i32> 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.