public function child($name) {
        $file = $this->getChild($name);
        if (is_dir($file)) {
            return new static($file);
        }
        if (is_file($file)) {
            return new File($file);
        }
        return false;
    }
public function child($name) {
        $file = $this->getChild($name);
        if (is_dir($file)) {
            return new static($file);
        }
        if (is_file($file)) {
            return new File($file);
        }
        return false;
    }
public function child ( $ name ) { $ file = $ this -> getChild ( $ name ) ; if ( is_dir ( $ file ) ) { return new static ( $ file ) ; } if ( is_file ( $ file ) ) { return new File ( $ file ) ; } return false ; }
GET FILE BY NAME IN THIS DIRECTORY
@param string $name 文件名
@return bool|FileObject
GET FILE BY NAME IN THIS DIRECTORY