On Tue, May 24, 2011 at 10:44, Vinzent Steinberg <vinzent.steinb...@googlemail.com> wrote: > On 24 Mai, 05:08, Matthew <mrock...@gmail.com> wrote: >> You're right - it's unclear if this should be an event or a random >> variable. Thanks for the heads up on 'or'. I was hoping to use | for >> 'given' in the future. I'll figure this out when I get there. Isn't >> '==' ok to use though? Isn't it __eq__? I thought that 'is' was the >> forbidden one. > > '==' is forbidden too, because it is Python equality and not > mathematical equality. E.g. in Python: > >>>> (x + 1)**2 == x**2 + 2*x + 1 > False
Note that what Vinzent and Ronan mean is not that *Python* forbids overriding __eq__ to return other objects. numpy, SQLAlchemy, and several other libraries do that just fine. Rather, sympy has decided, as a matter of *policy*, to define __eq__ methods in such a way as to return a bool, like most other types, in order to allow sympy objects to be used in a variety of contexts like most Python objects you will encounter. In particular, most sympy objects can be used as dictionary keys or set members. -- Robert Kern "I have come to believe that the whole world is an enigma, a harmless enigma that is made terrible by our own mad attempt to interpret it as though it had an underlying truth." -- Umberto Eco -- You received this message because you are subscribed to the Google Groups "sympy" group. To post to this group, send email to sympy@googlegroups.com. To unsubscribe from this group, send email to sympy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sympy?hl=en.
