Temporarily Redirect stdout/stderr

Question

Is it possible to temporarily redirect stdout/stderr in Python (i.e. for the duration of a method)?

Edit:

The problem with the current solutions (which I at first remembered but then forgot) is that they don't redirect; rather, they just replace the streams in their entirety. Hence, if a method has a local copy of one the variable for any reason (e.g. because the stream was passed as a parameter to something), it won't work.

Any solutions?

Answer 1

You can also put the redirection logic in a contextmanager.

import os import sys  class RedirectStdStreams(object):     def __init__(self, stdout=None, stderr=None):         self._stdout = stdout or sys.stdout         self._stderr = stderr or sys.stderr      def __enter__(self):         self.old_stdout, self.old_stderr = sys.stdout, sys.stderr         self.old_stdout.flush(); self.old_stderr.flush()         sys.stdout, sys.stderr = self._stdout, self._stderr      def __exit__(self, exc_type, exc_value, traceback):         self._stdout.flush(); self._stderr.flush()         sys.stdout = self.old_stdout         sys.stderr = self.old_stderr  if __name__ == '__main__':      devnull = open(os.devnull, 'w')     print('Fubar')      with RedirectStdStreams(stdout=devnull, stderr=devnull):         print("You'll never see me")      print("I'm back!")