Use of custom error types and switch on error types

go-custom-errors

package main

import (
	"fmt"
)

type ErrorType1 struct {
	Message string
}

func (e *ErrorType1) Error() string {
	return "type1 - " + e.Message
}

type ErrorType2 struct {
	Message string
}

func (e *ErrorType2) Error() string {
	return "type2 - " + e.Message
}

func main() {
	var error1 error
	error1 = &ErrorType1{"test"}
	switch es := error1.(type) {
	case *ErrorType1:
		fmt.Printf("should be type1: %v\n", es)
	case *ErrorType2:
		fmt.Printf("should be type2: %v\n", es)
	}

	var error2 error
	error2 = &ErrorType2{"test"}
	switch es := error2.(type) {
	case *ErrorType1:
		fmt.Printf("should be type1: %v\n", es)
	case *ErrorType2:
		fmt.Printf("should be type2: %v\n", es)
	}
}