type IoUtil … type osIOHandler … // NewIOHandler Create a new IoHandler implementation func NewIOHandler() IoUtil { … } func (handler *osIOHandler) ReadFile(filename string) ([]byte, error) { … } func (handler *osIOHandler) ReadDir(dirname string) ([]os.FileInfo, error) { … } func (handler *osIOHandler) Lstat(name string) (os.FileInfo, error) { … } func (handler *osIOHandler) EvalSymlinks(path string) (string, error) { … }