Writer helper to handle errors

main.go

package main

import (
	"fmt"
	"io"
	"os"
)

func main() {

	ew := &errWriter{Writer: os.Stdout}
	fmt.Fprintf(ew, "Hello, World!\n")

	if ew.err != nil {
		fmt.Fprintf(os.Stderr, "error: %v\n", ew.err)
	}
}

type errWriter struct {
	io.Writer
	err error
}

func (e *errWriter) Write(buf []byte) (int, error) {
	if e.err != nil {
		return 0, e.err
	}

	var n int
	n, e.err = e.Writer.Write(buf)
	return n, nil
}