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From: Doug Orleans <dougo@ccs.neu.edu>
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Date: Mon, 15 Nov 1999 16:11:56 -0500 (EST)
To: Karl Lieberherr <lieber@ccs.neu.edu>
Subject: Re: correct response
In-Reply-To: <199911141751.MAA23434@alnitak.ccs.neu.edu>
References: <199911141751.MAA23434@alnitak.ccs.neu.edu>
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Karl Lieberherr writes:
 > Hi Doug:
 > 
 > do you agree that second set of "at *"
 > below is correct?
 > 
 > This refers to the tricky zigzag example.
 > 
 > -- Karl
 > 
 > /proj/adaptive/www/course/exams/m-3360-f99/q3/zigzag-special-DJ
 > at A
 > at B
 > at B
 >  at X t0
 >  at X t1
 >  at B t1
 >  at C t1

I don't understand the question!  Are you asking if your
hand-generated traversal is equal to "from A via B to C"?
It's not.

You have:

  class A {
    public void t0( ) {
      x.t0();
    }
  }

  class X {
    void t0(){
      System.out.println(" at X t0");
      b.t1();
    }
    void t1(){
      System.out.println(" at X t1");
      b.t1();
      c.t1();
    }
  }

  class B {
    void t1(){
      System.out.println(" at B t1");
    } 
  }

  class C { 
    void t1(){
       System.out.println(" at C t1");
    } 
  }

but I think it should be something like:

  class A {
    public void t0( ) {
      x.t0();
    }
  }

  class X {
    void t0(){
      super.t0_bef();
      System.out.println(" at X t0");
      super.t0(); // this is essentially what's missing in the
		  // Demeter/Java-generated code
    }
    void t1(){
      super.t1_bef();
      System.out.println(" at X t1");
      b.t1(); // actually we're calling t0 and t1 in parallel on b,
	      // because the nodeset models non-deterministically
	      // going down both paths
      c.t1();
    }
  }

  class B {
    void t0_bef() {
      System.out.println(" at B t0");
    }
    void t0() {
      this.t1();
    }
    void t1_bef(){
      System.out.println(" at B t1");
    } 
    void t1() {
      // do nothing; premature termination
      // (to catch t1() on an E-object)
    }
  }

  class C { 
    void t1(){
       System.out.println(" at C t1");
    } 
  }