example1.go

// All material is licensed under the Apache License Version 2.0, January 2004
// http://www.apache.org/licenses/LICENSE-2.0

// Sample program to show how the default error type is implemented.
package main

import "fmt"

// http://golang.org/pkg/builtin/#error
type error interface {
	Error() string
}

// http://golang.org/src/pkg/errors/errors.go
type errorString struct {
	s string
}

// http://golang.org/src/pkg/errors/errors.go
func (e *errorString) Error() string {
	return e.s
}

// http://golang.org/src/pkg/errors/errors.go
// New returns an error that formats as the given text.
func New(text string) error {
	return &errorString{text}
}

func main() {
	if err := webCall(); err != nil {
		fmt.Println(err)
		return
	}

	fmt.Println("Life is good")
}

// webCall performs a web operation.
func webCall() error {
	return New("Bad Request")
}