turning python output into string variable using exec()

Question

I want to turn python output into string variable using exec()

Something like this is the goal:

code = "print(3)"
string = exec(code) # string should then equal 3

Sorry if this was repeated. I couldn't find the solution anywhere. Thanks

• sleblanc: You must explain why you absolutely need to use exec(), as solutions that do not use exec are almost always more elegant than those that do.

Answer 1

Actually contextlib provides a context manager that capture the stdout of your code called redirect_stdout.

Here is an example:

import io
from contextlib import redirect_stdout
func_str = 'print(3)'
stdout = io.StringIO()
with redirect_stdout(stdout):
 exec(func_str)
out = stdout.getvalue()
print(out, out.strip() == '3')

Output:

3
 True

PS: The code is inspired from contextlib.redirect_stdout documentation code example.

• sleblanc: Nice find! I was thinking about writing my swap_stdout function in my answer as a context manager, but I see there is already one in the stdlib that does it.