[Python-3000] Wither PEP 335 (Overloadable Boolean Operators)? (original) (raw)

Robert Kern robert.kern at gmail.com
Sun May 20 02:19:24 CEST 2007

Raymond Hettinger wrote:

Giovanni Bajo wrote:

Another workaround could be: Before focusing mental talents on workarounds and implementations, it would be worthwhile to consider whether the idea would help or hurt the language. The and/or keywords already have some complexity due to their returning non-boolean values. IMO, it would be a disservice to the language to further complexify their meanings. Right now, at least, we can make a static reading of the code and have a good idea of what the and/or keywords mean.

It would probably hurt the language, and for the record, I'm against it. We already have problems with rich comparisons not reliably returning booleans. It's a fairly common occurrence to do equality testing against generic data types. For example, finding if an object is in a list with list.index(). However, this does not reliably work when == can return something that is not interpretable as a boolean value like numpy arrays do. I don't think rich comparisons are a mistake (I use them much more frequently than I use list.index(), for example), but propagating the uncertainty further is probably a mistake. For numpy, the bitwise operators |&~ work fine on boolean arrays, and that's all such operators really need to work on.

-- Robert Kern

"I have come to believe that the whole world is an enigma, a harmless enigma that is made terrible by our own mad attempt to interpret it as though it had an underlying truth." -- Umberto Eco

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