On Sat, Mar 15, 2014 at 7:01 PM, Alexander Belopolsky <ndar...@mac.com> wrote: > > On Sat, Mar 15, 2014 at 2:25 PM, Alexander Belopolsky <ndar...@mac.com> > wrote: >> >> On Fri, Mar 14, 2014 at 11:41 PM, Nathaniel Smith <n...@pobox.com> wrote: >>> >>> Here's the main blocker for adding a matrix multiply operator '@' to >>> Python: we need to decide what we think its precedence and associativity >>> should be. >> >> >> I am not ready to form my own opinion, but I hope the following will help >> shaping the discussion. > > > One more question that I think should be answered by the PEP and may > influence the associativity decision is what happens if in an A @ B @ C > expression, each operand has its own type that defines __matmul__ and > __rmatmul__? For example, A can be an ndarray, B a sympy expression and C a > pyoperator.
The general rule in Python is that in a binary operation A # B, then first we try A.__special__, and if that doesn't exist or it returns NotImplemented, then we try B.__rspecial__. (The exception is that if B.__class__ is a proper subclass of A.__class__, then we do it in the reverse order.) -- Nathaniel J. Smith Postdoctoral researcher - Informatics - University of Edinburgh http://vorpus.org _______________________________________________ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
