> you can't overwrite a io.FileIO().name attribute A FileIO instance uses a dict for 'name' (msg214670): >>> vars(sys.stdin.buffer.raw) {'name': '<stdin>'} >>> f = tempfile.TemporaryFile() >>> vars(f.raw) {'name': 3} The name is optional meta-information. If it gets deleted, the repr falls back on using the file descriptor: >>> f.raw <_io.FileIO name=3 mode='rb+'> >>> del f.raw.name >>> f.raw <_io.FileIO fd=3 mode='rb+'>