[CZT-Devel] Re: zlive sets

[Petra M. <pe...@cs...>]

Hi Leo,

Leo wrote:
> In zlive set implementations for EvalSet interface, I noticed there are 
> corresponding visitor classes
> (eg. FlatDiscreteSetVisitor). I couldn't find any examples (or Javadoc) 
> of using such visitors.

You can find a general introduction into the visitor design pattern used 
in CZT in our ZB 2005 paper:
CZT---A Framework for Z Tools
I will send you a copy of this.

> For waht purpose they were introduced?

FlatDiscreteSet extends FlatPred which extends Pred and therefore Term. 
That is, a FlatDiscreteSet needs to implement the method
   Object accept(Visitor visitor);
defined in the Term interface. To be properly visitable one needs the
FlatDiscreteSetVisitor interface.

I do not know what Mark is planning to do with FlatDiscreteSets, but 
almost every tool that traverses an AST is implemented as a visitor.

Cheers,
Petra