In support of https://medium.com/@peter.gtz/thinking-about-new-ways-of-error-handling-in-go-2-e56d116952f1

CopyFile-new-syntax.go

func CopyFile(src, dst string) fails_with error {
	r := os.Open(src) on_error err fail fmt.Errorf("in Open %s %s: %v", src, dst, err)
	defer r.Close() on_error {}

	w := os.Create(dst) on_error err fail fmt.Errorf("in Create %s %s: %v", src, dst, err)

	io.Copy(w, r) on_error err {
		w.Close() on_error {} // explicitly ignore error
		os.Remove(dst) on_error {} // explicitly ignore error
		fail fmt.Errorf("in Copy %s %s: %v", src, dst, err)
	}

	w.Close() on_error err {
		os.Remove(dst) on_error {} // explicitly ignore error
		fail fmt.Errorf("in Close %s %s: %v", src, dst, err)
	}
}