How do I return to the default output (cell output) in Google Colab? Reassign sys.stdout to sys.__stdout__ doesn't seem to be working

Question

I'm trying to save results from printing the help of a function in a file, instead of presenting them on the cell output in Google Colab.

My code is below:

import sys
import io

def capture_help_to_buffer(obj):
    output_buffer = io.StringIO()
    sys.stdout = output_buffer

    try:
        help(obj)
    except:
        pass

    sys.stdout = sys.__stdout__
    return output_buffer.getvalue()

# Example usage
help_output = capture_help_to_buffer(list)
print(help_output)

My problem is: after running this code, print starts returns nothing. In other words: it seems that the reassiging of sys.stdout to its supposedly default value (sys.__stdout__) is not working.

My question: to what value should I reassign sys.stdout so print will return to its normal behavior (presenting its output in Google Colab's cell's output)?

Answer 1

You could solve this with contextlib.redirect_stdout, like so:

import sys
import io

from contextlib import redirect_stdout


def capture_help_to_buffer(obj):
    output_buffer = io.StringIO()

    with redirect_stdout(output_buffer):
        try:
            help(obj)
        except:
            pass

    return output_buffer.getvalue()

This creates a context in which stdout is redirected then restored when you exit the code block.

Here's the contextlib.redirect_stdout documentation: https://docs.python.org/3/library/contextlib.html#contextlib.redirect_stdout