[Python-Dev] Conditional expressions and sequences (original) (raw)

Skip Montanaro skip@pobox.com (Skip Montanaro)
Tue, 16 Oct 2001 11:04:51 -0500 

Paul> Now in your new syntax this is essentially

Paul> x = if condition then t else f

Paul> Therefore it would be cool if the implementation was
Paul> x=condition.__where__(t,f). This slot could be overwritten by
Paul> classes like Numeric's array. If condition was a list this might
Paul> be useful too.

Unfortunately, that requires both t and f to be evaluated. In a NumPy setting that's probably not a big deal because in most cases both values will be used in the resulting output. In a scalar context, the short-circuit nature of the expression is often important. If implemented as any kind of function you've lost that capability.

-- Skip Montanaro (skip@pobox.com) http://www.mojam.com/ http://www.musi-cal.com/