[Python-Dev] vox populii illiterati (original) (raw)

Tim Peters tim.one@comcast.net
Sun, 09 Feb 2003 12:15:44 -0500

[Neal Norwitz]

... One thing to note, many people are saying you can currently do:

cond and truevalue or falsevalue However, many have gotten it wrong, either by reversing the true/false value or by using something in the truevalue which may be false (sometimes even constants). pychecker tries to find this condition (when truevalue is a false constant), but it does a poor job of determining the idiom IIRC.

Indeed, that's been the most amazing part of the discussion to me. Not so much the form above: everyone gets that wrong in the case true_value may actually be false, but I don't agree they're prone to swap the values. But virtually everyone got the order wrong when rewriting examples with the weaker

(false_value, true_value)[cond]

variant (they swap the values in the tuple). That's evidence that the expression-like workarounds don't really work for real people.

The other really interesting stuff has been Andre Dalke digging into mounds of C++ code, and finding bad (or at best dubious) uses of ?:. I believe his claim that if Python grows a conditional expression, lots of people coming from C will use it out of habit instead of learning that min(), max() and abs() are built in. That's evidence that people are people .