[julvo]

The problem with this is, that the caller of the function which returns what you wrote (i.e. a dynamic error message) can't match the error anymore for conditional error handling. That's because errors in go are just strings. I guess a solution could be to provide an error matching function but that seems quite cumbersome compared to typed errors.

[majewsky]

This problem has been addressed in Go 1.13 with wrapped errors. If you get an error from a filesystem operation, you can

  return fmt.Errorf("ListThings failed: %w", err)

which is a different error type, but the caller can downcast it into the original filesystem error type (even across multiple layers of wrapping) if they're interested in specifically these types of errors.

[arp242]

You should never match against "err.Error()" for conditional error handling, a better solution is to use a custom error type. There are a bunch of different ways to approach this in Go.

[julvo]

Ah that's better, thanks. here a link for others who are reading this https://gobyexample.com/errors

[apta]

Except most libraries do nothing of the sort, so you end up having to do a substring search.

[arp242]

I've rarely run in to this, but if you do then I'd expect most people will be happy to accept a PR.