Joe Corneli wrote: > I'm not sure how to do the following: > > I have a list A, that grows, shrinks, and changes. > > I want to have a list B that includes list A within > its list structure, along with other things, and that > automatically keeps the "A" part of itself in synch > with A. > There will certainly be some kid gloves involved because most of the normal things you might want to do with A are destructive or subversive to any pointer B might hold. The reason is, B is a symbol in an obarray that points to a list element. That list element might have a CDR which points to the same list element that A points to but a change to A list can never cause the pointer held by some element in list B to change. So any operation involving setq A will very likely cause the corresponding pointer in list B to point to an obsolete location.
> Is there a way to accomplish this? And if it can't be done with > list structure alone, what other suggestions can you make? I'm pretty sure this is not what you are looking for since the position of the contents of B within list A is fixed. (defmacro a+b () '`(,@A ,@B)) ;or any number of similar things (setq A '(a b c d)) (setq B '(1 2 3 4)) (a+b) => (a b c d 1 2 3 4) (setq a '(w x y z)) (setq b '(9 8 7 6)) (a+b) => (w x y z 9 8 7 6) To be honest, I can't think of a way to do what it seems you want in *any* language. But maybe I don't really understand. _______________________________________________ Help-gnu-emacs mailing list [email protected] http://lists.gnu.org/mailman/listinfo/help-gnu-emacs
