[SciPy-User] subclassing ndarray : i want slice to return > ndarray, not subclass

M Daoust m_daoust@hotmail....
Thu May 24 05:40:25 CDT 2012

> > Subclassing ndarray is a very tricky business -- I did it once and
> > regretted having done it for years, because there's so much you can't do
> > etc.. You're almost certainly better off with embedding an array as an
> > attribute, and then forward properties etc. to it.
> Yes, it's almost always the wrong thing...

I've sub-classes numpy.ndarray in some of my personal code, so I'm just 
hoping to understand why this is the wrong choice before I dig the 
hole any deeper.

So it's only wrong because it's hard to do right, and you can't do certain things? (which things?)

If you want a object to act mostly like a  numpy.ndarray, making a sub-class *should* be the right answer. 

Because isn't forwarding lookups to a wrapped class  just a re-implementation of the sub-classing mechanism?

Isn't it also tricky to get that "wrapping subclassing" right?

If you're going to sub-class something, it would be nice to use the built in sub-class machinery, for clarity... etc...

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