exception message output problem

[Russ P.]

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.Inconsis tentUnits: 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.Inconsis tentUnits: ('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 InconsistentUni ts(Exception):
def __init__(self, args=""): self.args = args

and here is my instantiation of it:

raise scalar.Inconsis tentUnits, 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 from http://RussP.us/scalar.htm
.. A complete user guide is available. Check it out. I think you'll
like it.

[Russ P.]

On Dec 22, 5:34 am, Fredrik Lundh <fred...@python ware.comwrote:

Russ P. wrote:

Actually, the parens aren't needed, so this works too:

def __init__(self, args=""): self.args = args,

The trailing comma wasn't necessary a while back (pre 2.5?), so
something in Python must have changed. I'd say that it looks a bit
cleaner without the trailing comma, so maybe whatever changed should
get changed back.

as the name implies, "args" is supposed to be a sequence, and is stored
internally as a tuple. if something has changed, it's probably that 2.5
enforces this behaviour via a property.

to fix your code, just replace your own __init__ method with a "pass",
and leave the initialization to the Exception class itself.

That works. And because it is the simplest solution here, I'd say it's
the "correct" solution. Thanks.

[Florian Diesch]

Lie <Li******@gmail .comwrote:

# Python have an odd (read: broken) singleton implementation
# single member tuple must have a comma behind it

Otherwise (1+2)+(3+4) would evaluate to (3, 7) instead of 10.

Florian
--
<http://www.florian-diesch.de/>
-----------------------------------------------------------------------
** Hi! I'm a signature virus! Copy me into your signature, please! **
-----------------------------------------------------------------------