Bounds checking

[Martin De Kauwe]

> Offhand, my only quibble is that sys.exit is not helpful for debugging.  
> Much better to raise an error:
>
>         if not self.funcTable.get(attribute, lambda x: True)(value):
>             raise ValueError ('error out of bound')
>
> or define a subclass of ValueError just for this purpose.  On error, the
> program will stop just as dead, but you'll get a trace.
>
>         Mel.

I think generally I prefer my code to die and as long as I know where
(from the statement) the error occurred I know generally what point I
have to debug up until. Can you explain how your solution would be
easier with a trace as I don't tend to use the raise/assert
functionality so I am interested.

thanks