[Python-Dev] PySet_Next (Was: PySet API) (original) (raw)

"Martin v. Löwis" martin at v.loewis.de
Sun Mar 26 21:50:43 CEST 2006

Raymond Hettinger wrote:

Pardon, I bungled the terminology. PySetNext returns a borrowed reference. That is problematic is arbitrary Python code can be run afterwards (such as PyObjectHash in the example).

Not really. It is under the control of the caller of PySet_Next what (if any) Python code is invoked, and getting this correct is straight-forward (once you know that it yields borrowed references).

I don't know what specific application Barry has in mind, but I'm sure he can get it right (although it might be an interesting experiment to test that theory :-) In general, I would expect that people find it easier to get code involving PyDict_Next right than code dealing with iterators - primarily because of the error cases you have to consider.

We have a perfectly good way to iterate with PyIterNext(). It may take a couple of extra lines, but it is easy to get correct and has no surprises. It seems that the only issue is that Barry says that he refuses to use the iterator protocol. Heck, just turn it into a list and index directly. There is no need to muck-up the set api for this.

I don't care that much either way, although I would prefer to see an actual, current use case for PySet_Next, rather than theoretical, made-up examples. I don't expect to use Python sets in C code at all, personally.

Regards, Martin

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