displays funny characters, like spaces or control characters, more
clearly (one of my pet peeves in error messages). Also only suppress
the filename if it is None; display it if it is '', since that would
be a genuine (illegal) filename passed in!
involve a filesystem path. To that end:
- Changed IOError to EnvironmentError and added a hack which checks
for arg of len 3. When constructed with a 3-tuple, the third item
is the filename and this is squirreled away in the `filename'
attribute. However, for in-place unpacking backwards
compatibility, self.args still only gets the first two items. Added
a __str__() which prints the filename if it is given.
- IOError now inherits from EnvironmentError
- New class OSError which also inherits from EnvironmentError and is
used by the posix module.
errors are handled (these gave ``TypeError: not enough arguments'').
Also changed its __str__() to correct a typo (missing self.) and
return str(self.msg) to ensure the result is always string.
Also changed the default __str__ to simply return str(self.args).