[Python-Dev] Rationale for sum()'s design?

[Brett C.]

Nick Coghlan wrote:
> Guido van Rossum wrote:
> 
>> On Tue, 15 Mar 2005 00:05:32 +1000, Nick Coghlan 
>> <ncoghlan at iinet.net.au> wrote:
>>
>>> ...   try:
>>> ...     value += first
>>> ...   except TypeError:
>>> ...     raise TypeError("Cannot add first element %r to initial value 
>>> %r" % (first, value))
>>
>>
>>
>> No, no, no! NO! Never catch a general exception like that and replace
>> it with one of your own. That can cause hours of debugging pain later
>> on when the type error is deep down in the bowels of the += operation
>> (or perhaps deep down inside something *it* invoked).
> 
> 
> Ouch. Obviously, I hadn't thought about that. . .
> 
> Wasn't there a concept floating around some time ago to support 
> exception chaining, so additional context information could be added to 
> a thrown exception, without losing the location of the original problem?
> 

Yes, but it didn't go anywhere.  See 
http://www.python.org/dev/summary/2003-06-01_2003-06-30.html#pep-317 for the 
summary.

-Brett