Alan Isaac schrieb: > Miles wrote: > >> What boolean operation does '-' represent? > > > Complementation. > And as usual, a-b is to be interpreted as a+(-b). > In which case the desired behavior is > False-True = False+(-True)=False+False = False
I always thought, at least in a Python context, A-B would trigger A.__sub__(B), while A+(-B) triggers A.__add__(B.__neg__()). A better choice could be A+~B (A.__add__(B.__invert__())) because it's always unary (and IMO slightly more visible). > In response to Stargaming, Steve is making > a point about the incoherence of certain arguments, > not proposing an implementation. Why should it be incoherent? Bjoern is pointing out an important aspect of how Python handles binary algebra (correctly). In contrast, Steven tries to invert his argument. Following, I showed why Steven's proof is wrong because his implementation fails at some aspects where the current one works. So I cannot see how Bjoern's argument is either wrong or not relevant. -- http://mail.python.org/mailman/listinfo/python-list
