Ondrej Certik wrote: > Hi, > > Aaron is now with me in Los Alamos and we are trying to figure out how > to nicely incorporate the Constant class inside SymPy, it's currently > in this branch: > > http://github.com/asmeurer/sympy/tree/constant-Mul > > and it works, however, as you can see, it need modifications in the > Add and Mul classes, and that's bad. The same goes to the Order class, > which also needs special handling in Mul and Add, and that's bad too. > > I would like to find a solution, so that people can hook up their own > classes inside sympy and it would just work, yet the core would not > have to be modified. One thing that we figured out is to use a > handler, essentially Basic() would have some fast handler, that would > work for symbols and be fast (using dictionaries). But then Constant > and Order could override that handler and do their own stuff, like > O(x)+x -> O(x) and similar things, for which the default handler will > fail, because O(x) != x, and thus the dictionary approach will fail.
My solution for bringing queries out of the core (I think it's a similar problem) was also to consider handler you can add/remove at runtime. There was a resolution problem, which I solved with a dictionary mapping objects to handlers. You can see source code here: http://fseoane.net/cgi-bin/gitweb.cgi?p=sympy.git;a=tree;f=sympy/queries;h=c5a1752ed44513d5d7185924e072e126cae6ae4a;hb=refs/heads/queries If you look at the tests, the last two are about extensibility, just to show how easy it is to add new types to the system. > > If anyone has any ideas how to approach this, it'd be awesome --- just > throw your idea here, no matter how crazy it is. > > Ondrej > > > > -- http://fseoane.net/blog/ --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
