[Python-Dev] PySet API (original) (raw)

Raymond Hettinger raymond.hettinger at verizon.net
Thu Mar 30 06:09:45 CEST 2006

[Raymond Hettinger]

> Barry, go ahead with PySetClear().

[Barry] Cool thanks. I think we've also compromised on _PySet_Next(), correct?

Yes, _PySet_Next() is a good compromise for you and me -- it saves you from writing a hack and saves my API from including a bug factory. The only issue is that Martin thinks it to be a crummy idea. Personally, I have no problem with putting-in an undocumented hook for daring people who aspire to swim in quicksand ;-)

[Raymond Hettinger]

> The story is different for PySetUpdate(). Defining it now could get in the > way > of possible future development for the module (the function may end-up > taking a > variable length argument list instead of a single argument).

So why not just go ahead and do that now? If you know that's what you want eventually, why wait? From my perspective, adding a NULL at the end of the argument list wouldn't be that big of a deal.

[Barry]

BTW, I'm willing to do the work on this. I'm already going to update my patch anyway to reflect our current decisions, so I'm happy to do this while I'm at it. I'll try to get a new patch posted in a day or so.

The idea is not yet ready for prime-time. If I do it for one of the named operations, I will do it for all (to keep the interface uniform). I haven't yet had the time to work-out the math on whether it would be worthwhile and provide some differential advantage over simply repeating the same operation several times over. My research question is whether work can be saved by controlling the order of operations -- the concept is somewhat like optimizing multi-term matrix multiplication where the total work effort can vary dramatically depending on which matrices are multiplied together first, A((BC)D) vs (AB)(CD) vs (A(BC))D etc. Put in business terms, the question is whether I'm able to leverage the associative and commutative properties of some chained set operations. FWIW, the module already has optimizations to take advantage of the commutative property of binary AND, OR, and SYMMETRIC_DIFFERENCE operations. However, the multi-term optimization probably wait until Py2.6 -- it is too experimental for now.

Raymond

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