Idiomatic way to return/break if Err/None

• rust

  2,683 93,041 10.0 Rust

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Looks good to me. There is some work on simplifying this “extract value or diverge” pattern (let…else, RFC 3137), but that’s still some ways away. You can also use the ? operator to return from the function early. There is also ongoing work on try blocks which allow reducing the scope of error propagation (RFC 243), but again, I don’t expect this to hit stable soon.

• thiserror

  14 4,021 8.7 Rust

  derive(Error) for struct and enum error types

The idiomatic way of doing this is making sure you always return results with error types that are convertible. How do you do this? One way is to use thiserror. You define your library's error type using it and you wrap lower error types in it, add from's using the macro, etc. This way you avoid all the cumbersome conversion and just let the ? operator or a map handle it for you.

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• anyhow

  13 5,059 8.5 Rust

  Flexible concrete Error type built on std::error::Error

Alternatively, if you've got a lot of error types and you're outside a library (so directly in a binary where you don't plan to reuse code elsewhere) you can use anyhow. This gives you an error type you can basically propagate any other error through. On top of that you can attach context information at every return. It's basically a more complicated Result>.

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