Python AttributeError：NoneType对象没有属性'close' [英] Python AttributeError: NoneType object has no attribute 'close'

问题描述

这是我的代码。

  from sys import argv 
 out_file = open（argv [2]，'w'）。write（open（argv [1]）。read （））
 out_file.close（）
  

我得到了标题中列出的AttributeError。为什么我打开写入方法（argv [2]，'w'）out_file没有指定文件类型？

解决方案

out_file 被分配给 write 方法，它是 None 。把这个语句分成两个部分：
$ b $ $ $ $ $ $ $ $ $ $ $ out_file = open（argv [2]，'w'）
out_file.write （open（argv [1]）。read（））
out_file.close（）

真的，最好这样做：

  with open（argv [1]）as in_file，open argv [2]，'w'）as out_file：
 out_file.write（in_file.read（））
  

使用和语句意味着Python会自动关闭 in_file 和 out_file 当执行离开时，块。

I am learning python and I wrote a script that copies the content of one text file to another.

Here is my code.

from sys import argv
out_file = open(argv[2], 'w').write(open(argv[1]).read())
out_file.close()

I get the AttributeError listed on the title. Why is it that wen I call the write method on open(argv[2], 'w') the out_file is not assigned a File type?

Thank you in advance

解决方案

out_file is being assigned to the return value of the write method, which is None. Break the statement into two:

out_file = open(argv[2], 'w')
out_file.write(open(argv[1]).read())
out_file.close()

And really, it'd be preferable to do this:

with open(argv[1]) as in_file, open(argv[2], 'w') as out_file:
    out_file.write(in_file.read())

Using with with statement means Python will automatically close in_file and out_file when execution leaves the with block.

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