Exception Messages

[MRAB]

On 2012-10-15 17:22, John Gordon wrote:
> In <mailman.2217.1350317845.27098.python-list at python.org> MRAB <python at mrabarnett.plus.com> writes:
>
>> > Why wasn't the message printed out?
>>
>> You didn't add a __str__ method:
>
>> class PvCamError(Exception):
>>      def __init__(self, msg):
>>          self.msg = msg
>>      def __str__(self):
>>          return self.msg
>
> Wouldn't PvCamError inherit __str__() from Exception?
>
Yes, but you've put the message in msg, and Exception doesn't have that
attribute.

An alternative approach would be:

class PvCamError(Exception):
     pass