Ternery operator

[Uwe Schmitt]

Peter Hansen <peter at engcorp.com> wrote:
> Uwe Schmitt wrote:
>> 
>> Andrew Chalk <achalk at xxxmagnacartasoftware.com> wrote:
>> > Is there a python equivalent of the C ternery operator?
>> 
>> > I.e.:
>> 
>> > fred = (x == 1) ? 12 : 15
>> 

> I would think a *Python* equivalent to ?: should not use
> direct equality comparison with 1.  Better to drop the "==1"
> parts in any of the above, to allow the usual Python interpretation
> of what is True and what is False to occur.

> ...so fred = [12, 15][not x]  is sufficient.

You made a mistake, compare :

          [12,15][not x]      (x==1) ? 12 : 15

    x=0   15                  15

    x=1   12                  12

    x=2   12                  15   

Normaly you should simulate "C ? T : F"

either by
             [T,F][not C]

or

             (C and [T] or [F])[0]

in the first case T and F are evaluated allways,
the latter solution does short circuit evaluation,
which is according to the C/C++ semantics of the
ternary operator.

Greetings, Uwe.

-- 
Dr. rer. nat. Uwe Schmitt   http://www.procoders.net                      
schmitt at procoders.net      "A service to open source is a service to mankind."