Avoid checking if error is nil repetition?

Question

I\'m currently learning go and some of my code looks like this:

a, err := doA()
if err != nil {
  return nil, err
}
b, err := doB(a)
if err != nil {
  return nil         


        

Answer 1

If you have many of such re-occurring situations where you have several of these error checks you may define yourself a utility function like the following:

func validError(errs ...error) error {
    for i, _ := range errs {
        if errs[i] != nil {
            return errs[i]
        }
    }
    return nil
}

This enables you to select one of the errors and return if there is one which is non-nil.

Example usage (full version on play):

x, err1 := doSomething(2)
y, err2 := doSomething(3)

if e := validError(err1, err2); e != nil {
    return e
}

Of course, this can be only applied if the functions do not depend on each other but this is a general precondition of summarizing error handling.