Python：没有csv.close（）？ [英] Python: No csv.close()?

问题描述

我使用CSV模块读取制表符分隔的文件。代码如下：

I'm using the CSV module to read a tab delimited file. Code below:

z = csv.reader(open('/home/rv/ncbi-blast-2.2.23+/db/output.blast'), delimiter='\t')

.close（）到我的脚本的结尾我得到和错误说明csv.reader对象没有属性'关闭'

But when I add Z.close() to end of my script i get and error stating "csv.reader' object has no attribute 'close'"

z.close()

那么如何关闭Z？

推荐答案

读者真的只是一个解析器。当你请求一行数据时，它将读取操作委托给底层的文件对象，并将结果转换为一组字段。所以没有必要关闭读者;这将是一个无意义的操作。

The reader is really just a parser. When you ask it for a line of data, it delegates the reading action to the underlying file object and just converts the result into a set of fields. So there's no need to close the reader; it'd be a meaningless operation.

但是你应该确保关闭底层的文件对象。在Python 2.5+中，这是做到这一点的方式：

You should make sure to close the underlying file object, though. In Python 2.5+, here's the way to do that:

with open('/home/rv/ncbi-blast-2.2.23+/db/output.blast') as f:
    z = csv.reader(f, delimiter='\t')

如果您不熟悉 with 语句，它基本上将它的内容封装在 try ... finally 文件在 finally 部分。对于Python 2.5，您需要一个 __ future __ 导入以启用和语句。如果你需要保留与2.4的早期版本的兼容性，你应该使用 try ... finally 自己关闭。

If you're not familiar with the with statement, it basically encloses its contents in a try...finally block that closes the file in the finally part. For Python 2.5 you'll need a __future__ import to enable the with statement. If you need to retain compatibility with earlier versions of Python like 2.4, you should do the closing yourself using try...finally.

^{感谢 Jared 指出兼容性问题与语句。}

^{Thanks to Jared for pointing out compatibility issues with the with statement.}

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