Python Mystery Theatre -- Episode 1: Exceptions

[Peter Hansen]

Erik Max Francis wrote:
> 
>  > ACT II --------------------------------------------
> > >>> class MyMistake(Exception):
> > ...     pass
> >
> > >>> try:
> > ...     raise MyMistake, 'try, try again'
> > ... except MyMistake, msg:
> > ...     print type(msg)
> > ...
> >
> > <type 'instance'>
> 
> I'm not sure what mystery you're trying to get at here.  This is what
> Python prints for all instances:
[snip]

He's showing a case where a programmer thought he/she was using
a sort of "parallel form" with the "MyMistake, 'try, try again'"
part and the "MyMistake, msg" part.  

The programmer expected print type(msg) to show "<type 'str'>".  

This is probably an example of an error promoted by leaving the 
redundant "raise Class,args" form of exception-raising in Python, 
instead of having a single obvious way: "raise Class(args)" as 
would be more Pythonic. ;-)

-Peter