[Python-Dev] "DOS" error codes, WindowsError, and errno

["Martin v. Löwis"]

Guido van Rossum wrote:
> WindowsError should have used a different name for the Windows-native
> error code, so we could have defined both separately without
> confusion.
> 
> Is it too late to change WindowsError in that way?

We could define a different exception, say, Win32Error which inherits
from OSError, and has a POSIX errno in the errno attribute, and also
an additional attribute win32_error. We could then stop raising
WindowsError. So code that expects WindowsError will never see it, but
will see OSError instead (which it also should handle if it was written
portable).

Or we could just break the errno value in WindowsError, which would
make code that catches WindowsError continue to work, but break
code that looks for specific errno values in WindowsError. Code aiming
for backwards compatibility should then write

 except WindowsError, e:
   try:
      windows_error = e.windows_error
   except NameError:
      # Python 2.4 and earlier
      windows_error = e.errno

As for naming, I would like to avoid naming new things Win32: Microsoft
just changed the name of the API to "Windows API" (pointing out that
it isn't necessarily 32 bits anymore).

Regards,
Martin