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Date: Mon, 15 Oct 2012 17:34:50 +0100
From: MRAB <python@mrabarnett.plus.com>
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To: python-list@python.org
Subject: Re: Exception Messages
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Xref: csiph.com comp.lang.python:31319

On 2012-10-15 17:22, John Gordon wrote:
> In <mailman.2217.1350317845.27098.python-list@python.org> MRAB <python@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