On Mo, 2016-09-05 at 14:54 -0400, Marten van Kerkwijk wrote: > Hi Sebastian, > > Indeed, having the scalar pass through `__array_wrap__` would have > been useful (_finalize__ is too late, since one cannot change the > class any more, just set attributes). But that is water under the > bridge, since we're stuck with people not expecting that. > > I think the slightly larger question, but one somewhat orthogonal to > your suggestion of a new dundermethod, is whether one cannot avoid > more such methods by the new indexing routines returning array > scalars > instead of regular ones. > > Obviously, though, this has larger scope, as it might be part of the > merging of the now partially separate code paths for scalar and array > arithmetic, etc.
Thanks for the input. I am not quite sure about all of the things. Calling array wrap for the scalar returns does not sound like a problem (it would also effect other code paths). Calling it only for the new methods creates a bit of branching, but is not a big deal. Would it help you though? You could avoid implementing all the new indexing methods for many/most subclasses, but how do you tell numpy that you are supporting them? Right now I thought it would make sense to give an error if you try `subclass.vindex[...]` but the subclass has `__getitem__` implemented (and not overwritten vindex). The dundermethod gives a way to tell numpy: you know what to do. For the sake of masked arrays it is also convenient (you can use the indexer also on the mask), but masked arrays are rather special. It would be interesting if there are more complex subclasses out there, which implement `__getitem__` or `__setitem__`. Maybe all we need is some new trick for the scalars and most subclasses can just remove their `__getitem__` methods.... - Sebastian > > All the best, > > Marten > _______________________________________________ > NumPy-Discussion mailing list > NumPy-Discussion@scipy.org > https://mail.scipy.org/mailman/listinfo/numpy-discussion >
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