Two things- 1.) I think we should stick to the current mechanics framework's ideology of not letting the user initialize a base scalar/vector. As I have commented on your PR, we can define __getattr__ and __getitem__ methods for the CoordSys class, which would enable a user to use the 3rd (say) basis vector with R.3, and the 3rd base scalar with R[3]
2.) Now, coming to the creation of base vectors/scalars. I like your idea of caching them. The main reason I feel this should be done is, we don't really need two or more instances of a base vector/scalar in one run. So, we can define a helper method to initialise a base scalar- _generate_base_vector(coordsys, index) Hence, when the user says R[2], R's __getitem__ will call '_generate_base_vector(self, 2)'. Now we can use function memoization for this method. We can create a custom cache which stores a tuple of the coordinate system and the index as the key. So the next time the same method is called for R[2], the pre-generated instance will be returned. Same can be done for basis vectors. I had written a blog post about function memoization, and I guess it will work here with some modification. 1) and 2) will eliminate any ambiguity regarding base vectors/scalars and also provide a cleaner interface for the whole operation. On Sat, Jul 6, 2013 at 4:19 PM, Prasoon Shukla <prasoon92.i...@gmail.com>wrote: > @Gilbert, @Sachin, @Stefan : I am facing a bit of a problem that I have > written about in this week's blog > here<http://musingsofafriend.wordpress.com/2013/07/06/gsoc-week-3-sympy-development-finishing-the-basic-structure/>. > Please see the second part of the blog where I mention about a cache to > hold relationships between coordinate system and base scalars and base > vectors. Please comment your views here. > > -- > You received this message because you are subscribed to a topic in the > Google Groups "sympy" group. > To unsubscribe from this topic, visit > https://groups.google.com/d/topic/sympy/t-Je0beTIIU/unsubscribe. > To unsubscribe from this group and all its topics, 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. > > > -- 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.
