Boolean tests [was Re: Attack a sacred Python Cow]

Erik Max Francis max at alcyone.com
Wed Jul 30 08:16:43 CEST 2008


Russ P. wrote:

> On Jul 29, 10:33 pm, Carl Banks <pavlovevide... at gmail.com> wrote:
>> On Jul 30, 1:15 am, "Russ P." <Russ.Paie... at gmail.com> wrote:
> 
>>> Having said that, it would sure be nice to be able to write
>>> if myList is not empty:
>>> instead of
>>> if len(myList) != 0:
>> I can agree with this.
> 
> But I guess that could only work if there were only one empty list
> that represents all empty lists (as there is only one actual "None").
> I don't know if that makes sense or not.

It really doesn't, since it presumably wouldn't apply to just list 
types.  There are plenty of other sequence types:  such as tuples, 
strings, or even arbitrary custom types.  Emptiness is a test for the 
value of an object, not a test for whether it is identical to another 
object, so this is a very misleading of the `is` operator, bordering on 
abuse.

This syntax would make far less sense than the existing Boolean test.

-- 
Erik Max Francis && max at alcyone.com && http://www.alcyone.com/max/
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