[Python-Dev] Is implicit underscore assignment buggy?

[Bob Ippolito]

On Jun 7, 2006, at 3:41 PM, Aahz wrote:

> On Wed, Jun 07, 2006, Raymond Hettinger wrote:
>> Fredrik:
>>>
>>> for users, it's actually quite simple to figure out what's in the _
>>> variable: it's the most recently *printed* result.  if you cannot  
>>> see
>>> it, it's not in there.
>>
>> Of course, there's a pattern to it.  The question is whether it is  
>> the
>> *right* behavior.  Would the underscore assignment be more useful and
>> intuitive if it always contained the immediately preceding result,
>> even if it was None?  In some cases (such as the regexp example),  
>> None
>> is a valid and useful possible result of a computation and you may
>> want to access that result with _.
>
> My take is that Fredrik is correct about the current behavior being  
> most
> generally useful even if it is slightly less consistent, as well as  
> being
> undesired in rare circumstances.  Consider that your message is the  
> only
> one I've seen in more than five years of monitoring python-dev and
> c.l.py.

I agree. I've definitely made use of the current behavior, e.g. for  
printing a different representation of _ before doing something else  
with it.

-bob