Hi, On 2 Apr 2011, at 20:33, Alexandre Bergel wrote: Yes. Bounds is about the bounds of the figure. A Shape object is a strategy and it is shared among multiple elements. Thus, it cannot hold data specific to one element. I believe the below issues really stem from what we understand by Element. As I said, in the very original version of Mondrian, we had Figure and Graph separately. The Figure was responsible for the position and size. The Graph was a container. Afterwards, we merged the two structures to have less objects and to have less indirection which kind of made the code harder to follow. So, Graph was merged in, and in the end we only had Figures. The idea of Mondrian was to focus on the presentation, so Figure is really what it says: a Figure :). And like a figure, it has a position and a size, and it knows how to draw itself on a physical canvas, and how to deal with interaction. That is quite well defined. Now, you renamed Figure to Element, which as I said from the beginning does not really convey the original idea. And because of this name, now we can start to say that the job of the Figure is not part of the responsibilities of an Element. While this could be a possible direction, it goes away from the original idea. I am just wary about adding more layers if there aren't strong reasons for it. On the other hand, it can well be that it scales in the end. So, we can experiment but we should be careful to trace the effects :) In the original Mondrian, we actually could have graphs in the edges to model fancy annotations on the edge. We had some experiments, but in the end we did not really manage to get the bounds of the subgraph properly. The location is the job of the node :). The caching structure might be somewhere else, though. Cheers, Doru -- www.tudorgirba.com "To lead is not to demand things, it is to make them happen."

Hi, On 3 Apr 2011, at 13:55, Alexandre Bergel wrote: I do not understand. The Element (I really would call it Figure because it would convey much better the intention) that has to retain the instance variable. The logic that depends on the model is in the shape. In the case of bounds it delegates to Shape>>computeBoundsFor: It is great to want to simplify a design, but this would only happen if you introduce some extra concepts (like a Graph). However, this comes at a price, but maybe it is worth it. Regarding VW vs Pharo, I do not see where the Pharo version is less complex than the VW version. In fact, with the caching it is slightly more complex. Cheers, Doru -- www.tudorgirba.com "One cannot do more than one can do."