[Python-Dev] Currently baking idea for dict.sequpdate(iterable, value=True) (original) (raw)

Tim Peters tim.one@comcast.net
Mon, 25 Nov 2002 21:07:39 -0500

[Guido]

... Perhaps the current set implementation could be made faster by limiting it somewhat more? The current API attempts to be fast and flexible, but tends to favor correctness over speed where a trade-off has to be made. But maybe that's a poor way of selling a new built-in data type, and we would do better by having a truly fast implementation that is more limited? It's easier to remove limitations than to add them.

I don't think you can get "fast" membership testing unless sets inherit the C-level dict.contains directly. The time burden of going thru a Python contains method can't be overcome.

For all the rest, it's plenty fast enough for me. Note that the spambayes project uses sets freely, mostly for uniquification, but also for convenience in manipulating usually-small sets of email.Message objects. If you're going to do something with the set elements (which that project does), the time to uniquify the original sequence is likely (as it is in that project) trivial compared to the rest. For contexts requiring heavy-duty repeated membership testing, though, spambayes code still used a straight dict with values 1.

premature-etc-ly y'rs - tim