Sort files by one of it's attributes.
        
        **中文文档**
        
        对容器内的WinFile根据其某一个属性升序或者降序排序。

def sort_by(self, attr_name, reverse=False):
        """Sort files by one of it's attributes.
        
        **中文文档**
        
        对容器内的WinFile根据其某一个属性升序或者降序排序。
        """
        try:
            d = dict()
            for abspath, winfile in self.files.items():
                d[abspath] = getattr(winfile, attr_name)
            self.order = [item[0] for item in sorted(
                list(d.items()), key=lambda t: t[1], reverse = reverse)]
        except AttributeError:
            raise ValueError("valid sortable attributes are: "
                             "abspath, dirname, basename, fname, ext, "
                             "size_on_disk, atime, ctime, mtime;")