On 4/8/2011 3:28 PM, Karsten Ahnert wrote: >> (Please don't top-post. Rearranging...) > > Hmm, I just used reply in my mail client. (Sorry for this double) > >>> Another question is: can a node have a state. In my algorithm it would >>> be nice, if every proto::multiplies< > node stores some intermediate >>> values which are used during later evaluations of the tree. >> >> No. Intermediate expression nodes carry no run-time state in their >> nodes. They only carry compile-time information in the form of the tag. >> That's how a plus node is distinguished from a minus node, for instance. >> >> If you need to compute intermediate values, you can use a transform to >> build a parallel structure. > > Do you mean to build an entire new tree, or just to replace some nodes?
If only some nodes have associated intermediate result, then you could just replace some nodes. > In my current algorithm I use callable contexts to do the work. I think > this is more favorable since I have to evaluate the tree N times to obtain > the result. Why does that matter? Transforms are almost always a better choice. > I think it would be nice to replace some nodes and customizing > the evaluation context, such that these nodes can be used to store the > intermediates. If you're doing calculation *and* tree transformation, then drop the callable contexts. They can't do the job. -- Eric Niebler BoostPro Computing http://www.boostpro.com _______________________________________________ proto mailing list proto@lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/proto
