[Python-Dev] unifying os.rename semantics across platform (original) (raw)

skip@pobox.com (Skip Montanaro) skip@pobox.com (Skip Montanaro)
Tue, 22 May 2001 16:54:42 -0500

Couldn't figure out why this message never generated any comment. Turns out it didn't reach the list because the host I sent it from (dynamic4.tttech.com) couldn't be resolved. I just noticed it in my errors mailbox and am sending it out again.

It was brought to my attention a week ago by a client that os.rename semantics differ between Unix and Windows. On Unix, if the destination file already exists it is silently deleted. On Windows, an exception is raised. I was able to verify this for Python 2.0 on Windows98. I assume nothing changed for 2.1, but I can't verify that. (Windows trashed my partition table and my Linux root partition while I was downloading 2.1. Consequently, I no longer run Windows. Take that, Bill...) I haven't checked the Mac yet (will do that when I get back to the US), but I think that os.rename should have the same semantics across all platforms. To the extent reasonably possible, I think this should also be true of other common functions exposed through the os module.

On the (unsupportable) theory that to-date, more Python apps have been written and/or deployed on Unix-like systems and that where Windows apps are concerned, many developers will have added a thin wrapper to mimic the Unix semantics, I think less breakage would result if the Unix semantics were implemented in the Windows version. It appears that is what POSIX compliance would demand as well.

Skip