Hi Doug:

>From dougo@ccs.neu.edu Fri Aug  1 16:43:29 1997
>From: Doug Orleans <dougo@ccs.neu.edu>
>To: Karl Lieberherr <lieber@ccs.neu.edu>
>Cc: boaz@ccs.neu.edu
>Subject: Re: special cases
>
>Karl Lieberherr writes:
> > Hi Boaz:
> > 
> > do you agree with the following two special cases?
> > I think that the first is not handled by our paper. We should add it.
> > 
> > Doug, how does your implementation handle those two special cases?
> > 
> > -- Karl
> > 
> > 
> > Special case 1:
> > =============================
> > 
> > Strategy graph S:
> > 
> > A (no edges, only one node)
> > ----------------
> > Class graph C:
> > 
> > A = B.
> > B = .
> > 
> > PathSet_S(C) = the single node path consisting of A.
> > 
> > This property is important so that we can say that a method
> > is a degenerate traversal: we visit only one object.
>
>This isn't currently expressible in Demeter/Java.  A strategy graph is
>defined as a nonempty list of edges.  I suppose I could modify it to
>allow an empty list.

Let's keep it the way it currently is since you have the other 
way of distributing code.


>
> > ===================
> > Special case 2:
> > =============================
> > 
> > 
> > Strategy graph S:
> > 
> > from A to A (two different strategy graph nodes)
> > ----------------
> > Class graph C:
> > 
> > A = .
> > 
> > PathSet_S(C) = the single node path consisting of A.
>
>Actually, the strategy graph "{ A -> A }" is represented as a single node
>with an edge to itself, rather than two separate nodes.  This probably
>needs to be changed, but for this case in particular I guess it
>doesn't make a difference.
>
>--Doug
>

I see: for strategy graphs same label means same node in
the current Demeter/Java.

Consider:

One_A: (Demeter/Java syntax and meaning)
{ A -> B bypassing {A,B}
  B -> A bypassing {A,B}
}

Two_A:
{ x1:A -> B     bypassing {A,B}
  B    -> x3:A  bypassing {A,B}
}

Here, there is a difference between the two:

A B A B A

is accepted by One_A but not by Two_A.

Since you allow several forms of expression for strategies:

StrategyExpression      : StrategyGraph | PathDirective | StrategyVariable
			| CompoundStrategy.

your policy: "same label implies same node" seems to be a good one
for StrategyGraph.
Why don't you keep that and we will see whether we get into
problems.


-- Karl