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Comment by throwaway894345

5 years ago

The trouble I’ve had as a beginner is crafting error types for those “Union of multiple existing error types”. E.g., myfunc() can return an IO error or a Parse error. The boilerplate for creating a new error type (absent macros) is significant, and while I’m aware that there are macro crates available which automate this, it’s not clear to me which of these if any are “most standard” or otherwise how to distinguish between them.

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throwaway894345

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Celeo  5 years ago

There are many ways to do it, like you said. Over time, the most popular options have shifted as new support from the standard library arrived. How you handle the errors can boil down to whether or not you really care about what kind of error it is, or just if an error occurred.

Two popular crates for handing these situations are thiserror [1] and anyhow [2], for handling errors by type and handling all errors, respectively.

There are additional ways, like just returning a Box wrapper around the stdlib error type [3], or just unwrapping everything. It depends on what your program needs.

[1] https://crates.io/crates/thiserror

[2] https://crates.io/crates/anyhow

[3] https://play.rust-lang.org/?version=stable&mode=debug&editio...