exception message output problem

[Lie]

On Dec 22, 2:57 am, "Russ P." <Russ.Paie... at gmail.com> wrote:
> I am baffled about why my exception messages are not displaying
> properly.
>
> I have a class that represents physical scalars with units. If I type
>
> >>> 3 * s + 4 * m
>
> I should get something like this:
>
> scalar.InconsistentUnits: 3 s, 4 m
>
> to show that seconds cannot be added to meters.  Instead, the message
> is broken up into individual characters, like this:
>
> scalar.InconsistentUnits: ('3', ' ', 's', ',', ' ', '4', ' ', 'm')
>
> This worked correctly for months, so I don't understand what went
> wrong. I am using version 2.5.1 on a Dell workstation with Red Hat
> Enterprise WS Linux.
>
> As far as I can tell, I am doing everything "by the book." Here is my
> exception class:
>
>     class InconsistentUnits(Exception):
>         def __init__(self, args=""): self.args = args
>
> and here is my instantiation of it:
>
>         raise scalar.InconsistentUnits, str(self) + ", " + str(other)
>
> I've tried various little changes, but nothing seems to make any
> difference. Has anyone else noticed this sort of behavior? Thanks.
>
> By the way, my scalar class is available for free fromhttp://RussP.us/scalar.htm
> . A complete user guide is available. Check it out. I think you'll
> like it.

The problem is in the InconsistentUnits Exception. It seems that the
act of:
self.args = 'Some String'
would break the string into chars, possibly because self.args think
'Some String' is a tuple of some sort.

Change the exception into this:
class InconsistentUnits(Exception):
        def __init__(self, args=""): self.args = (args,)
# Python have an odd (read: broken) singleton implementation
# single member tuple must have a comma behind it