Context::with_err is private about failure

[cramertj]

There's a context method on the Fail trait that you can use-- it calls Context::with_err internally.

[U007D]

Thanks, @cramertj, I'll give that a shot.

[withoutboats]

Yep, the intent is you create a context with Fail::context or (if you want to create one without an underlying error) with Context::new. Context::with_err is an implementation detail.

[U007D]

I guess I'm confused. In impl From... for Error above, I am wrapping a foreign error (which is not Fail);
I don't know how can I initialize Error::inner using Fail::context(), without a Fail instance available. Any ideas?

I'm also a bit puzzled on the asymmetry between using Fail::context for context with underlying error and Context::new for context without underlying error. I've no doubt there are valid implementation reasons for the split, but I wonder if the ergonomics could be improved by supporting both scenarios under Fail with Fail::context for context without an underlying error and Fail::context_err for context with an underlying error (or something similar). Thoughts?

[U007D]

Ah, nvm. I see now that Fail::context is supposed to be used in error's throw path, rather than at its declaration point. That clears up my confusion.