Github: https://github.com/mcmah309/error_set
Following a recent discussion on reimagining Rust, many voiced the need for more terse error handling. While anyhow and thiserror serve their purposes, each comes with its trade-offs. This got me thinking: Is there a middle ground that combines flexibility with precision?
Enter error_set a concept derived from Zig that elegantly balances the definition of possible errors within a given scope while remaining succinct and developer-friendly.
Here’s a sneak peek of how it looks:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
error_set! {
MediaError = {
IoError(std::io::Error)
} || BookParsingError || DownloadError || ParseUploadError;
BookParsingError = {
MissingBookDescription,
CouldNotReadBook(std::io::Error),
} || BookSectionParsingError;
BookSectionParsingError = {
MissingName,
NoContents,
};
DownloadError = {
InvalidUrl,
CouldNotSaveBook(std::io::Error),
};
ParseUploadError = {
MaximumUploadSizeReached,
TimedOut,
AuthenticationFailed,
};
}
With error_set, we no longer need “god enums” that are used in scopes where some variants can never happen. Instead we can tersely define the errors in scope and coerce them into a superset if propagated up the call stack.