On Fri, Feb 6, 2009 at 5:18 PM, Pierre GM <pgmdevl...@gmail.com> wrote:
> > On Feb 6, 2009, at 4:25 PM, Darren Dale wrote: > > > > > I've been looking at how ma implements things like multiply() and > > MaskedArray.__mul__. I'm surprised that MaskedArray.__mul__ actually > > calls ma.multiply() rather than calling > > super(MaskedArray,self).__mul__(). > > There's some under-the-hood machinery to deal with the data, and we > need to be able to manipulate it *before* the operation takes place. > The super() approach calls __array_wrap__ on the result, so *after* > the operation took place, and that's not what we wanted... > It looks like there are enough cases where manipulation needs to happen on the way in that it might be useful to consider a mechanism for doing so. It could avoid the need for lots of wrappers and decorators down the road. > > > Maybe that is the way ndarray does it, but I don't think this is the > > right approach for my quantity subclasses. If I want to make a > > MaskedQuantity (someday), MaskedQuantity.__mul__ should be calling > > super(MaskedQuantity,self).__mul__(), not reimplementations of > > numpy.multiply or ma.multiply, right? > > You'll end up calling ma.multiply anyway > (super(MaskedQuantity,self).__mul__ will call MaskedArray.__mul__ > which calls ma.multiply... So yes, I think you can stick to the > super() approach in your case > > > > > There are some cases where the default numpy function expects > > certain units on the way in, like the trig functions, which I think > > would have to be reimplemented. > > And you can probably define a generic class to deal with that instead > of reimplementing the functions individually (and we're back to the > initial advice). > > > > But aside from that, is there anything wrong with taking this > > approach? It seems to allow quantities to integrate pretty well with > > the numpy builtins. > > Go and try, the problems (if any) will show up... > Oh boy...
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