[Python-Dev] Re: Trinary Operators (original) (raw)

Gerald S. Williams gsw@agere.com
Thu, 6 Feb 2003 16🔞43 -0500

Guido van Rossum wrote:

> For example, with regard to short-circuiting, it will be > inconsistent with other expressions at some level in > either form or function.

How so? [ ... ] if x and y: print 1 else print 0 means the same as print 1 if x and y else 0

That's what I figured.

In that case, the "inconsistency in form" is the order of evaluation. The expression in the middle is evaluated, then either the one on the left or the one on the right. Not everyone will see this as a big issue, but it is a potential source of confusion. I did qualify my statement with "at some level". :-)

Compare this to the order of evaluation in the current equivalent (parentheses for clarity only): (x and y) and 1 or 0

or if you prefer: ((x and y) and [1] or [0])[0]

The order of evaluation is the same, but the form is different. If you are expecting short-circuiting, it's clear in this case that it's left-to-right.

-Jerry