如何使已打开的文件可读(例如 sys.stdout)? [英] How does one make an already opened file readable (e.g. sys.stdout)?

问题描述

我试图在字符串中获取 sys.stdout 的内容.我尝试了显而易见的:

I was trying to get the contents of sys.stdout in a string. I tried the obvious:

def get_stdout():
    import sys

    print('a')
    print('b')
    print('c')

    repr(sys.stdout)

    contents = ""
    #with open('some_file.txt','r') as f:
    #with open(sys.stdout) as f:
    for line in sys.stdout.readlines():
        contents += line
    print(contents)

但这给出了错误:

Exception has occurred: UnsupportedOperation
not readable

那么我该如何更改已打开文件的权限?

So how do I just change the permissions of that already opened file?

我试过了:

    sys.stdout.mode = 'r'

但这仍然会出现相同的错误...

but that still gives the same error...

其他可行的方法是以独立于硬件的方式让我获得 stdout 的名称/路径.

Other things that would work would be to just get me the name/path of stdout in a hardware independent way.

另一件可行的事情是让我在以字符串形式运行主脚本后，将 sys.stdout 的内容放入.

Another thing that would just work is letting me to put the contents of sys.stdout after I've run my main script in a string.

如果您遇到像我这样的错误，这些可能是相关的:为什么 __builtins__既是模块又是字典 Python:__builtin__ 之间有什么区别和 __builtins__?

these might be relevant if you are getting bugs like I am: why __builtins__ is both module and dict Python: What's the difference between __builtin__ and __builtins__?

错误:

line 37, in my_print
    __builtins__["print"](*args, file=f)  # saves to file
TypeError: 'module' object is not subscriptable

---

我读过的问题没有帮助:

---

Questions I've read that did not help:

• 使文件在 Python 中可写和可读立>
• TypeError:预期的字符串、字节或os.PathLike 对象，而不是 _io.TextIOWrapper
• 发送未修改的内容在python中通过电子邮件打印语句

推荐答案

可以使用以下代码:

import sys
from builtins import print as builtin_print
myfile = "output.txt"
def print(*args):
    builtin_print(*args, file=sys.__stdout__)    # prints to terminal
    with open(myfile, "a+") as f:
        builtin_print(*args, file=f)    # saves in a file

这应该重新定义 print 函数，以便它打印到 stdout 和您的文件.然后您可以从文件中读取.

This should redefine the print function so that it prints to stdout and to your file. You can then read from the file.

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