Proposal: errors.Pop()

[pkg]

Proposal: errors.Pop()

[davecheney]

You can write errors.Pop yourself

if err, ok := err.(interface{Cause() error}); ok {
      cause := err.Cause()
      ///
}

[davecheney]

Thank you for this suggestion. I understand what you want to implement, but I do not understand why. Can you show me how a caller of Pop would use the result?

[tux-eithel]

Hi!
I'm also agree with @bobbytables.
In my case a Pop() function is useful to isolate my library errors form others library.
Sometimes I wrap errors inside my function (which returns error), other times no.

var (
    ErrNetwork = errors.New("network erorr")
    ErrDB      = errors.New("database erorr")
)

func main() {

    err := funcWithError()

    switch errors.Pop(err) {
    case ErrNetwork:
        // do stuff
    case ErrDB:
        // do stuff
    default:
        // do other stuff
    }

...
}

[davecheney]

@tux-eithel thanks for your comment. I don't think your sample code works because the errors returned from this package cannot be compared for equality. This is by design.

[cris-hart]

@davecheney My example it too much simplified. The Pop() may returns an errors and the switch could be done on after call Error() function.

var (
    ErrNetwork = errors.New("network erorr")
    ErrDB      = errors.New("database erorr")
)

func main() {

    err := funcWithError()

    pop := errors.Pop(err)

    switch pop.Error() {
    case ErrNetwork:
        // do stuff
    case ErrDB:
        // do stuff
    default:
        // some error from other libraries
    }

...
}