如何在python中安全打开/关闭文件2.4 [英] How to safely open/close files in python 2.4

问题描述

我正在使用Python编写一个使用我们的服务器的小脚本。服务器只安装了Python 2.4.4。

I'm currently writing a small script for use on one of our servers using Python. The server only has Python 2.4.4 installed.

我没有开始使用Python，直到2.5出来，所以我习惯了以下形式：

I didn't start using Python until 2.5 was out, so I'm used to the form:

with open('file.txt', 'r') as f:
    # do stuff with f

但是，2.5之前没有语句的 m无法找到手动清理文件对象的正确方法的示例。

However, there is no with statement before 2.5, and I'm having trouble finding examples about the proper way to clean up a file object manually.

使用旧版本的python时，安全处理文件对象的最佳做法是什么？ / p>

What's the best practice for disposing of file objects safely when using old versions of python?

推荐答案

使用 try / finally ：

f = open('file.txt', 'r')

try:
    # do stuff with f
finally:
    f.close()

这样可以确保即使＃do f with f 引发异常， f 仍将被正确关闭。

This ensures that even if # do stuff with f raises an exception, f will still be closed properly.

请注意，打开应该出现在之外 尝试。如果打开本身引发异常，则该文件未打开，不需要关闭。另外，如果打开引发异常，它的结果是不分配给 f ，它是调用 f.close（）的错误。

Note that open should appear outside of the try. If open itself raises an exception, the file wasn't opened and does not need to be closed. Also, if open raises an exception its result is not assigned to f and it is an error to call f.close().

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