The Go Programming Language

7.8 The error Interface

Since the beginning of this book, we’ve been using and creating values of the mysterious predeclared error type without explaining what it really is. In fact, it’s just an interface type with a single method that returns an error message:

type error interface {
    Error() string
}

The simplest way to create an error is by calling errors.New, which returns a new error for a given error message. The entire errors package is only four lines long:

Click here to view code image

package errors

func New(text string) error { return &errorString{text} }

type errorString struct { text string }

func (e *errorString) Error() string { return e.text }

The underlying type of errorString is a struct, not a string, to protect its ...