r2d2::Error should derive PartialEq and Clone about r2d2 HOT 4 CLOSED

Very few error types in the ecosystem implement those traits. You'll probably have a hard time with that design more broadly.

from r2d2.

Is that a good reason not to, though?

If you think it would harm the library in any way, then sure. But otherwise, with such a simple error type, I don't see any reason to restrict possible uses of it by not deriving.

And yes - wrapping generally isn't preferred. But sometimes it's a nice middle ground for internal code between properly embedding the contents of the error while adding context (like you ideally would in a library use case) and resorting to something like anyhow for application code.

Anyway, if you still disagree, I understand. Feel free to close and I'll work around it by embedding a to_string() of r2d2's error.

from r2d2.

It prevents this error type from ever including something not Clone or not PartialEq.

from r2d2.

Very true.

It occurred to me to check what serde does, and it doesn't implement PartialEq either. That led me to this issue with some relevant discussion: serde-rs/json#271, with one of the downstream suggestions being to use assert_matches!. This is better for all parties - ergonomic tests, good errors, and no need to derive just for tests.

Closing this issue as not planned.

from r2d2.