package fmt
Stringer is implemented by any value that has a String method, which defines the “native” format for that value. The String method is used to print values passed as an operand to any format that accepts a string or to an unformatted printer such as Print.
Golang fmt.Stringer type usage example
func toString(a interface{}) (string, bool) {
aString, isString := a.(string)
if isString {
return aString, true
}
aBytes, isBytes := a.([]byte)
if isBytes {
return string(aBytes), true
}
aStringer, isStringer := a.(fmt.Stringer) // <-- here
if isStringer {
return aStringer.String(), true // <-- and here
}
return "", false
}
Reference :
http://golang.org/pkg/fmt/#Stringer
