Is it possible to get the erroneous variable when getting a NameError exception?

[Steven D'Aprano]

On Fri, 25 Dec 2009 17:29:48 +0200, Dotan Barak wrote:

> Hi.
> 
> I'm trying to evaluate a string and getting a NameError (it is expected,
> since the variable my_number wasn't provided in the "locals"
> dictionary).
> 
> <--snip start-->
>  >>> eval("my_number < 10", {"__builtins__":None}, {})
> Traceback (most recent call last):
>    File "<stdin>", line 1, in ?
>    File "<string>", line 0, in ?
> NameError: name 'my_number' is not defined
> <--snip end-->
> 
> My question is: how can i know which variable name / symbol causes the
> NameError exception?
> In my example, this symbol is my_number.
> 
> Using that information, I will be able to print a nice error message to
> the user.

You mean just like the error message that Python already prints?

NameError: name 'my_number' is not defined

Don't waste your time re-inventing the wheel. But if you do insist on 
reinventing the wheel, here are some tools to help you:

try:
    my_number
except NameError, e:
    print str(e)
    print type(e)
    print e.args


-- 
Steven