On Wed, Sep 21, 2011 at 11:07 AM, Steven D'Aprano <steve+comp.lang.pyt...@pearwood.info> wrote: > If the right-hand argument is a subclass of the left-hand argument, AND also > defines __radd__ directly rather than inheriting it, then its __radd__ > method is called before the left-hand argument's __add__ method. > > which strikes me as a strangely specific and not very useful rule. I suspect > it might be an accident of implementation rather than a deliberate feature.
It makes sense, but in a weird way. (Maybe I understand it because I'm half Dutch? heh) It means that a subclass can override addition for itself - presumably, it'll define __add__ and __radd__ both - and that the only time you'd get a false positive (where a function thinks it can handle the addition but actually there's a better one) is when it's a subclass. So this is probably correct behaviour, but it's a fairly weird and esoteric rule. ChrisA -- http://mail.python.org/mailman/listinfo/python-list
