避免尝试 - 除了嵌套

Question

给定一个未知文件类型的文件,我想用多个处理程序之一打开该文件.如果无法打开文件,则每个处理程序都会引发异常.我想尝试所有这些,如果没有成功,提出异常.

我想出的设计是

filename = 'something.something'
try:
    content = open_data_file(filename)
    handle_data_content(content)
except IOError:
    try:
        content = open_sound_file(filename)
        handle_sound_content(content)
    except IOError:
        try:
            content = open_image_file(filename)
            handle_image_content(content)
        except IOError:
            ...

这种级联似乎不是正确的方法.

有什么建议？

Answer 1

也许您可以对所有处理程序进行分组并在for循环中对它们进行评估,如果没有成功则在最后引发异常.您还可以继续查看引发的异常,从中获取一些信息,如下所示:

filename = 'something.something'
handlers = [(open_data_file, handle_data_context), 
            (open_sound_file, handle_sound_content),
            (open_image_file, handle_image_content)
]
for o, h in handlers:
    try:
        o(filename)
        h(filename)
        break
    except IOError as e:
        pass
else:
    # Raise the exception we got within. Also saves sub-class information.
    raise e