The requested feature would require an additional argument to fdopen() and open(), which already have many args. It would be better IMO to make the `name` attribute on file objects writeable.

By the way, right now (in 3.x) fdopen() gives you the file descriptor number, which is better than nothing:

>>> import os
>>> f = os.fdopen(2, "w")
>>> f
<_io.TextIOWrapper name=2 encoding='UTF-8'>