Py_single_input and the side-effects...

[Mark Lawrence]

On 05/06/2010 11:11, Gabriel Genellina wrote:
> On 31 mayo, 08:11, moerchendiser2k3<googler.
> 1.webmas... at spamgourmet.com>  wrote:
>
>> you are right, Python still holds the last
>> reference. I just set a dummy and thats it :)
>>
>> Can you tell me where did you get the information from?
>
> Do you mean the _ variable?
> It's in the tutorial:
> http://docs.python.org/tutorial/introduction.html#using-python-as-a-calculator
>
> --
> Gabriel Genellina

I have always believed that the _ variable is only available 
interactively because of this comment in the tutorial:-
"In interactive mode, the last printed expression is assigned to the 
variable _. This means that when you are using Python as a desk 
calculator, it is somewhat easier to continue calculations, for example: 
..."

However a thread from IIRC a couple of days back used _ to say "I'm not 
interested in you, I'm throwing you away" in a list comprehension or 
whatever.  I've tried this in a script this evening and it works perfectly.

print 'total', sum(amount for _, amount in outputs)

Where is the use of _ in a script documented, I've searched all over and 
can't find it, guess I don't have the Midas touch with google? :)

Kindest regards.

Mark Lawrence.