Hmm. It seems Python allows one-to-one relationships between objects. So, I did this:
In [64]: class Vector(object): ....: def __init__(self, coord_sys): ....: self.coord_sys = coord_sys ....: In [65]: class CoordSys(object): ....: def __init__(self): ....: self.vector = Vector(self) ....: In [66]: c = CoordSys() In [67]: c Out[67]: <__main__.CoordSys at 0x97b46cc> In [68]: c.vector Out[68]: <__main__.Vector at 0x97b42ac> In [69]: c.vector.coord_sys Out[69]: <__main__.CoordSys at 0x97b46cc> And this seems to work just fine. -- You received this message because you are subscribed to the Google Groups "sympy" group. To unsubscribe from this group and stop receiving emails from it, send an email to sympy+unsubscr...@googlegroups.com. To post to this group, send email to sympy@googlegroups.com. Visit this group at http://groups.google.com/group/sympy. For more options, visit https://groups.google.com/groups/opt_out.
