Hi Johan:

Your traversal implementation description in

http://www.ccs.neu.edu/research/demeter/design-decisions/TAO/jan11
Documentation.ps

gives a good introduction to TAO. It works, however, only for the most common
cases and is not general because it does not construct the 
traversal graph.

For Demeter/J (Java with traversal support) we will use a general solution
using the AP library.

In Demeter/J we have Strategy-objects, TraversalGraph-objects
and static methods long_get, long_collect and traverse of class Traversal.
The current class dictionary is kept in a static variable.

The methods long_get, long_collect and traverse take either a 
Strategy-object or a TraversalGraph-object as input.

TraversalGraph-objects are useful to have around to deal with
evolution of the class graph.

To do the run-time traversals Demeter/J uses reflection.
http://java.sun.com/docs/books/tutorial/reflect/object/invoke.html
From the TraversalGraph-object we know which  parts to traverse.
We assume that a traversable part x has a public get_x().
Using reflection, we retrieve the right Method-object and invoke it
using invoke.

-- Karl

Summary of classes for package TraversalSupport:

class Traversal
static Object long_get(Object o, Strategy s);
static Object long_get(Object o, TraversalGraph t);
static Iteration long_collect(Object o, Strategy s);
static Iteration long_collect(Object o, TraversalGraph t);
static Object traverse(Object o, Strategy s, Visitor v[]);
static Object traverse(Object o, TraversalGraph t, Visitor v[]);

class ClassGraph
ClassGraph(File f[]);
See: http://www.ccs.neu.edu/home/telliott/proposal.html

class Strategy
class StrategyEdge
class StrategyEdge_List
class Source
class Target
etc.
======== cd
Strategy =  List(StrategyEdge) .
StrategyEdge =  Source Target [Bypass].
Bypass = ClassName.
Source = <source> ClassName.
Target = <target> ClassName.

ClassName = Ident.
LabelName = Ident.

class TraversalGraph
TraversalGraph(ClassGraph cd, Strategy s);
TraversalGraph Intersection(traversalGraph t1, TraversalGraph t2);

class Visitor
// superclass of all visitors 

Phase 1:
Phase 1:
========

class Traversal
static Object long_get(Object o, Strategy s);

class ClassGraph
ClassGraph(File f[]);
See: http://www.ccs.neu.edu/home/telliott/proposal.html

class Strategy
class StrategyEdge
class StrategyEdge_List
class Source
class Target
etc.
======== cd
Strategy =  List(StrategyEdge).
StrategyEdge =  Source Target.
Source = <source> ClassName.
Target = <target> ClassName.

ClassName = Ident.
========

class TraversalGraph
TraversalGraph(ClassGraph cd, Strategy s);