[Python-Dev] cmp(x,x) (original) (raw)

Robert Ledwith rledwith at cas.org
Wed May 19 10:06:16 EDT 2004

Armin Rigo wrote:

... Unless there are serious objections I suggest to (i.e. I plan to) remove the short-cut in PyObjectRichCompareBool() -- performance is probably not an issue here -- and then review all built-in comparison methods and make sure that they return "equal" for identical objects.

I have a serious objection to this because it is a major performance problem. In my Python-2.3.3 code I had implemented an equivalent comparison test because of a performance bottleneck. The bottleneck involved looking up tuples in huge dictionaries of tuples (millions of tuples per dictionary). Putting in a simple equality test reduced the run time of programs by as much as 50%; since each program took days to run, this was a substantial improvement for me. I was considering posting this as a bugfix when I discovered that it had already been incorporated into the CVS.

For the sake of people such as myself who use Python to perform large-scale symbolic processing, please consider other approaches to solving the NaN situation before removing this code.

:s Robert H. Ledwith INET: rledwith at cas.org :s Unless explicitly stated to the contrary, nothing in this posting should :s be construed as representing my employer's opinions.

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