can error messages be improved or can they be overridden ?

[Stef Mientki]

thanks RDM,
I finally had a case where I really needed it,
so it tried,
works perfect,
except the marked lines should be indented 1 more.
cheers,
Stef

rdmurray at bitdance.com wrote:
> "andrew cooke" <andrew at acooke.org> wrote:
>   
>> rdmurray at bitdance.com wrote:
>> [...]
>>     
>>> (You know, I really ought to revisit that routine and make it part
>>> of my standard development toolbox.)
>>>       
>> please post it....
>>     
>
> OK.  I dug it up, cut out the stuff that was specific to the application,
> freshened it up a little, and added a little demo.  I don't claim this
> is the best possible way to do this (it certainly could be made smarter,
> possibly by using python facilities to actually parse the line; right
> now it takes a very brute force approach to trying to find variables),
> but it served my purposes and perhaps it will help others.
>
> Oh, yeah, and I just added the globals bit without thoroughly testing
> it...I think it probably doesn't help much and may be misleading when
> the traceback is thrown in an imported module.
>
> Enjoy.
>
> --RDM
>
> ------------------------------------------------------------------
> from traceback import format_tb, format_exception_only
> from sys import exc_info
> from re import compile
> varsplitter = compile("[^0-9a-zA-Z_]")
>
> def format_exception():
>     """
>     Add a dump of any variables we can identify from the failing program
>     line to the end of the traceback.  The deep mojo for doing this came
>     from an example in the Zope core plus documentation in the Python
>     Quick Reference.
>     """
>     etype, value, tb = exc_info()
>     plaintb = format_tb(tb)
>     result=['Traceback (innermost last):']
>     for line in plaintb:
>         result.append(line)
>         f = tb.tb_frame
>         tb = tb.tb_next
>   
>
>     * locals=f.f_locals
>     * vars = varsplitter.split(line.split('\n')[-2])
>     * dvars = set()
>     * self = None
>     * if 'self' in locals: self = locals['self']
>     * for v in vars:
>     * if v in dvars: continue
>     * dvars.add(v)
>     * if v in locals:
>     * result.append(' %s: %r\n' % (v,locals[v]))
>     * if self and hasattr(self, v):
>     * result.append(' self.%s: %r\n' % (v,getattr(self, v)))
>     * if v in globals():
>     * result.append(' (global) %s: %r\n' % (v,globals()[v]))
>
>     result.extend(format_exception_only(etype, value))
>     return ''.join(result)
>
>
> class Demo:
>     y = 200
>     def __init__(self, x):
>         self.x = x
>
>     def bad(self):
>         x = [1, 2]
>         y = (5, 9, 9)
>         y[1] = x[2] + foo
>
> foo = 'a value'
>
> def main():
>     bar = Demo('some value')
>     bar.bad()
>
>   
> if __name__=='__main__':
>     try: main()
>     except Exception:
>         print format_exception()
>
> ------------------------------------------------------------------
> rdmurray at maestro:~>python tb.py
> Traceback (innermost last):  File "tb.py", line 56, in <module>
>     try: main()
>   File "tb.py", line 52, in main
>     bar.bad()
>   File "tb.py", line 46, in bad
>     y[1] = x[2] + foo
>       y: (5, 9, 9)
>       self.y: 200
>       x: [1, 2]
>       self.x: 'some value'
>       (global) foo: 'a value'
> IndexError: list index out of range
> ------------------------------------------------------------------
>
> --
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>