[Python-Dev] Traceback style

[Guido van Rossum]

> > Ka-Ping Yee <ping@lfw.org>:
> > > With the suggested changes, this would print as
> > > 
> > >     Traceback (innermost last):
> > >       Line 1 of <stdin>
> > >       Line 3 of <stdin>, in Spam.eggs
> > >     AttributeError: ham

ESR:
> > IMHO, this is not a good idea.  Emacs users like me want traceback
> > labels to be *more* like C compiler error messages, not less.

Ping:
> I suppose Python could go all the way and say things like
> 
>     Traceback (innermost last):
>       <stdin>:3
>       foo.py:25: in Spam.eggs
>     AttributeError: ham
> 
> but that might be more intimidating for a beginner.
> 
> Besides, you Emacs guys have plenty of programmability anyway :)
> You would have to do a little parsing to get the file name and
> line number from the current format; it's no more work to get
> it from the suggested format.

Not sure -- I think I carefully designed the old format to be one of
the formats that Emacs parses *by default*: File "...", line ...  Your
change breaks this.

> (What i would really like, by the way, is to see the values of
> the function arguments on the stack -- but that's a lot of work
> to do in C, so implementing this with the help of repr.repr
> will probably be the first thing i do with sys.displaytb.)

Yes, this is much easier in Python.  Watch out for values that are
uncomfortably big or recursive or that cause additional exceptions on
displaying.

--Guido van Rossum (home page: http://www.python.org/~guido/)