Hi Josh:

Sorry to hear you are sick. My entire family was (I was lucky and had
only a mild reaction).

I don't come in today.

Work to be done:
(please take Doug's note into account at end of message)

Implement:
static Object longGet(Object o, TraversalGraph t);
(using reflection)

You have to do also Atusa's work, i.e. reusing:

http://www.ccs.neu.edu/home/telliott/proposal.html

Coordinate with Doug how to best use the AP Library.

I hope longGet will work on simple examples when I am back.

-- Karl

======================
Hi Atusa:

Here is a more detailed description of the first phase of your project.
First phase is at very end. Josh will help you as described below.

A prerequisite of the project is to have read (for Josh in detail algorithm 2):
http://www.ccs.neu.edu/research/demeter/biblio/strategies.html

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 longGet(Object o, Strategy s);
static Object longGet(Object o, TraversalGraph t);
static Iteration longCollect(Object o, Strategy s);
static Iteration longCollect(Object o, TraversalGraph t);
static Object traverse(Object o, Strategy s, Visitor v[]);
static Object traverse(Object o, TraversalGraph t, Visitor v[]);
static Method getAccessor(ClassName cn, PartName pn); //Josh
// returns method object for accessor method of class
// cn and part pn

class ClassGraph
ClassGraph(File f[]);

class PartName

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) [Source] [Target].
StrategyEdge =  Source Target [Bypass].
Bypass = ClassName.
Source = <source> ClassName.
Target = <target> ClassName.

ClassName = Ident.
LabelName = Ident.

class TraversalGraph
TraversalGraph(ClassGraph cd, Strategy s);
void traverse (Object o, Visitor v[]);  //Josh
TraversalGraph Intersection(traversalGraph t1, TraversalGraph t2);

class Visitor
// superclass of all visitors, generated 
Visitor()
void start();
void finish();
void before(X host);
void before_p(P source, Q dest);
void after(X host);
void after_p(P source, Q dest);

class SampleVisitor extends Visitor
Object get_return_val();

Phase 1:
========

class Traversal
static Object longGet(Object o, Strategy s);
static Method getAccessor(ClassName cn, PartName pn); //Josh
// returns method object for accessor method of class
// cn and part pn

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);
void traverse (Object o, Visitor v[]);  //Josh

class Visitor
// superclass of all visitors, generated
Visitor()
void before(X host);

===========================================
Collaboration between Josh and Atusa:

Josh provides the traversal graph code using the AP Library.
Atusa does not use the AP library directly, only through the 
methods Josh provides (getAccessor,traverse,etc.).

Atusa does the construction of cd from Java code.
Josh and Attusa need to agree on the class dictionary for class dictionaries.
==============

Hi Doug:

thank you for your feedback. I agree with you.
Josh: please can you update the interfaces/design document based on
Doug's feedback and send it to us.

>From dougo@ccs.neu.edu Thu Jan 14 17:07:06 1999
>From: Doug Orleans <dougo@ccs.neu.edu>
>Date: Thu, 14 Jan 1999 17:07:03 -0500 (EST)
>To: Karl Lieberherr <lieber@ccs.neu.edu>
>Cc: atoosa@ccs.neu.edu, jayantha@ccs.neu.edu, johan@ccs.neu.edu
>Subject: Re: your project
>
>Karl Lieberherr writes:
> > The methods long_get, long_collect and traverse take either a 
> > Strategy-object or a TraversalGraph-object as input.
>
>Maybe TraversalGraph could be a concrete subclass of the abstract
>class Strategy?  In some sense, it is a strategy, just a very detailed
>one.  (Other subclasses of Strategy would be PathDirective and
>StrategyGraph.)

That is a very good idea.

>
> > We assume that a traversable part x has a public get_x().
>
>Maybe we should use the Bean convention and call this getX()?

I agree.

>
> > static Object longGet(Object o, Strategy s);
> > static Iteration longCollect(Object o, Strategy s);
>
>I'm not really happy with these "long" names.  How about something
>like "retrieve" and "retrieveAll"?  Or "find/All"?  (As long as we
>don't conflict with the Java 2 collection hierarchy methods.)

I like find/All but is it already used?
long* has the advantage that a conflict is less likely.
>
> > static Method getAccessor(ClassName cn, PartName pn); //Josh
> > // returns method object for accessor method of class
> > // cn and part pn
>
>These arguments should probably just be Strings, if this is something
>the Java programmer will be expected to call.

You are right.
Use primitive types in DI interface: A personality recomendation.

>
> > class ClassGraph
> > ClassGraph(File f[]);
>
>Is this an array of Java source files?

That is what I had in mind.

>
>--Doug
>

-- Karl