Einstein summation notation (was: question of style)

Chris Rebert clp2 at rebertia.com
Fri Jul 17 08:30:39 CEST 2009


On Thu, Jul 16, 2009 at 11:13 PM, koranthala<koranthala at gmail.com> wrote:
>> That test was designed to treat None as a boolean False, without
>> noticing that numeric 0 is also treated as False and could make the
>> test do the wrong thing.  This is an extremely common type of error.
>
> Actually, I felt that 0 not being considered False would be a better
> option.
> I had lot of instances where 0 is a valid value and always I had to
> put checks specifically for that.
> For me, None and False should be equal to False in if checks, every
> thing else being considered True.
>
> Can someone let me know why 0 is considered equal to False?
> There should be real good reasons for it, only that I cannot think of
> one.

* Because that's how C does/did it (primary motivation)
- Because if Boolean algebra is implemented using numbers, False is 0
- Because philosophically, 0 is the "empty" or null value for numbers,
        and empty values are by convention considered false in Python
- Because it's the behavior people want 75% of the time.

FWIW, your paradigm of true/false is used by Lisp and Lisp wannabes
such as Ruby.

Cheers,
Chris
-- 
http://blog.rebertia.com



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