[Python-Dev] IO module precisions and exception hierarchy

[Greg Ewing]

Michael Foord wrote:

> Some of the error messages are truly awful though as things stand, 
> especially for someone new to Python. Try to read from a file handle 
> opened in read mode for example: IOError: [Errno 9] Bad file descriptor

Subdividing the IOError exception won't help with
that, because all you have to go on when deciding
which exception to raise is the error code returned
by the OS. If the same error code results from a
bunch of different things, there's not much Python
can do to sort them out.

The error messages produced for the various error
codes could perhaps be improved, but that's an
orthogonal issue.

-- 
Greg