baderrors.go

baderrors.go

package main

import "fmt"

// make a custom error type
type MyError struct{}

// satisfy the Error interface
func (e *MyError) Error() string {
	return ""
}

func customErrorReturnWithType() *MyError {
	var err *MyError // if you are unfamiliar with go, declaring but not intializing a variable like this
	return err       // initializes to what is called the "zero value", which is nil for pointer types
}

func customErrorReturn() error {
	var err *MyError
	return err
}

func main() {
	sane := customErrorReturnWithType() // return type is '*MyError'
	fmt.Printf("%v\n", sane == nil)     // it's nil

	insane := customErrorReturn()       // return type is just 'error'
	fmt.Printf("%v\n", insane == nil)   // wat
}