On Tue, May 19, 2015 at 4:41 AM, Carsten Knoll <[email protected]> wrote: > On 05/19/2015 07:48 AM, Joachim Durchholz wrote: >> >> An external dictionary isn't ideal but better than this, at least from >> the maintainer's perspective. >> >>>> Maybe we can give you better help if you describe your use case in some >>>> more detail. >>> >>> At some point I create symbols from which I know, that they are >>> derivatives and I want to store their order. Using the classes Function >>> and Derivative is no real option because I want the symbols to behave as >>> symbols on most occasions. >> >> Ah. This sounds like a design problem in Derivative to me that we should >> fix. >> Can you post what you did, what you'd have needed to get out, and what >> SymPy gave you? > > I think strongest argument for me was that the string representation of > the expressions gets too long for Functions and Derivatives. This > reduces my chance to "see" any structure. > > Second argument is that I have a (own) library for modeling differential > forms which internally uses Symbol and does not straight forwardly work > with Function instances. > > E.g. > > x.name -> 'x' > x(t).name -> AttributeError
That's because x(t) is not really an instance of x. Symbol implements __call__ so that x(t) returns a Function object (a completely different class). Aaron Meurer > > However, this discussions make me think, if using Functions would not be > the better alternative > >> >>> In general, I think there are situations, where it might be useful to >>> store some algorithm-specific extra information to some symbols. >> >> For algorithms of SymPy itself, I think the algorithms should be fixed :-) >> >> It would be useful for coding external algorithms, but it does come with >> ramifications (most importantly the potential for namespace conflicts); >> from a maintenance perpective, it's far better if such an algorithm does >> its own data management. > > OK. I can perfectly live with this. > > > > > -- > 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 [email protected]. > To post to this group, send email to [email protected]. > Visit this group at http://groups.google.com/group/sympy. > To view this discussion on the web visit > https://groups.google.com/d/msgid/sympy/555B0556.2040908%40gmx.de. > For more options, visit https://groups.google.com/d/optout. -- 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 [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/sympy. To view this discussion on the web visit https://groups.google.com/d/msgid/sympy/CAKgW%3D6Kq9AqMk1O97Of%2BPN_NUJEwf2obaCbYa4fHo45PdbFOWg%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
