Below is a class dictionary and the corresponding C++ class
interface. Find the unknowns.

A = <b> B.
B : C | D | A *common* <w> W.
W ~ {DemIdent}.
C = .
D = .

class B :  public Construction {
private:
  W* w;
  static const char* type;
public:
  B( W* = NULL );
  W* get_w() const { return( w ); }
  void set_w( W* new_w ) { w = new_w; }
  W* rset_w( W* );

  const char*        get_type() const { return( type ); }
#include "B.h"
};

class A : public B {
private:
  B* b;
  static const char* type;
public:
  A( B* = NULL );
  B* get_b() const { return( b ); }
  void set_b( B* new_b ) { b = new_b; }
  B* rset_b( B* );

  const char*        get_type() const { return( type ); }
#include "A.h"
};

typedef DemIdent* DemIdent_;
declare(list,DemIdent_);

class W : public DemIdent_list_ {
private:
  static const char* type;
public:
  W( DemIdent* first ) : DemIdent_list_( first ) { /* empty */ };
  W() { /* empty */ };
  const char*        get_type() const { return ( type ); }
#include "W.h"
};

class C : public B {
private:
  static const char* type;
public:
  C();
  const char*        get_type() const { return( type ); }
#include "C.h"
};

class D : public B {
private:
  static const char* type;
public:
  D();
  const char*        get_type() const { return( type ); }
#include "D.h"
};


A = "a" <b> B.
B : C | D | A *common* <w> W.
W ~ "(" {DemIdent} ")".
C = "c".
D = "d".

Consider the following three legal A-objects a1, a2, a3.
Find the unknowns.

A-object a1:
      : A ( 
         < b > : C ( 
            < w > : W { } ) 
         < w > : W { } ) 

A-object a2:
      : A ( 
         < b > : A ( 
            < b > : A ( 
               < b > : C ( 
                  < w > : W { } ) 
               < w > : W { } ) 
            < w > : W { } ) 
         < w > : W { } ) 

A-object a3:
      : A ( 
         < b > : A ( 
            < b > : D ( 
               < w > : W { 
                  : DemIdent "x" } ) 
            < w > : W { 
               : DemIdent "x" , 
               : DemIdent "y" , 
               : DemIdent "z" } ) 
         < w > : W { 
            : DemIdent "z" } ) } ) 

For A-object a1 above, write C++ statements which create that
object. Find the unknowns below.

C* c1 = new C();
c1 -> set_w(new W());
A* a1 = new A
  (c1);
a1 -> set_w(new W());

//      : A ( 
//         < b > : C ( 
//            < w > : W { } ) 
//         < w > : W { } ) , 


Consider the following illegal objects. Find the first error

A-object i1:
first error is on line UNKNOWN: replace letter UNKNOWN by UNKNOWN
      : A ( 
         < b > : A ( 
            < b > : D ( 
               < b > : C ( 
                  < w > : W { } ) 
               < w > : W { } ) 
            < w > : V { } ) 
         < v > : W { } ) 

A-object i1:
first error is on line UNKNOWN: UNKNOWN is missing.
      : A ( 
         < b > : A ( 
            < b > : D 
//	    ( 
//               < w > : W { 
//                  : DemIdent "x" } ) 
            < w > : W { 
               : DemIdent "x" , 
               : DemIdent "y" , 
               : DemIdent "z" } ) 
         < w > : W { 
            : DemIdent "z" } ) } ) 

C

*operation* void fun()
  *traverse*
    *from* A
      *via* D
    *to* F
  *wrapper* F
    *prefix*
      (@ cout << "in F " << endl; @)
  *wrapper* A
    *suffix*
      (@ cout << "after A-traversal " << endl; @)

A = <b> B <f1> F.
B = <c> C <f2> F.
C = <d> D <f3> F.
D = <e> E.
E = <f> F.
F = .
//  A  = <b > B 
//    <f1 > F .
void A::fun(  )
{ // outgoing calls
  this->get_b()->fun(  );
  // suffix class wrappers
 cout << "after A-traversal " << endl; }

//  B  = <c > C 
//    <f2 > F .
void B::fun(  )
{ // outgoing calls
  this->get_c()->fun(  ); }

//  C  = <d > D 
//    <f3 > F .
void C::fun(  )
{ // outgoing calls
  this->get_d()->fun(  ); }

//  D  = <e > E .
void D::fun(  )
{ // outgoing calls
  this->get_e()->fun(  ); }

//  E  = <f > F .
void E::fun(  )
{ // outgoing calls
  this->get_f()->fun(  ); }

//  F  = .
void F::fun(  )
{ // prefix class wrappers
 cout << "in F " << endl; }


A = <b1> B1 <f1> F.
B1 = <c1> C1.
C1 = <b> B.
B = <c> C <f2> F.
C = <d> D <f3> F.
D = <e1> E1 <f4> F.
E1 = <f5> F1.
F1 = <e> E.
E = <f> F.
F = .

//  A  = <b1 > B1 
//    <f1 > F .
void A::fun(  )
{ // construction edge prefix wrappers
  this->get_b1()->fun(  );
  // suffix class wrappers
 cout << "after A-traversal " << endl; }

//  B1  = <c1 > C1 .
void B1::fun(  )
{ // outgoing calls
  this->get_c1()->fun(  ); }

//  C1  = <b > B .
void C1::fun(  )
{ // outgoing calls
  this->get_b()->fun(  ); }

//  B  = <c > C 
//    <f2 > F .
void B::fun(  )
{ // construction edge prefix wrappers
  this->get_c()->fun(  ); }

//  C  = <d > D 
//    <f3 > F .
void C::fun(  )
{ // outgoing calls
  this->get_d()->fun(  ); }

//  D  = <e1 > E1 
//    <f4 > F .
void D::fun(  )
{ // outgoing calls
  this->get_e1()->fun(  );
  this->get_f4()->fun(  ); }

//  E1  = <f5 > F1 .
void E1::fun(  )
{ // outgoing calls
  this->get_f5()->fun(  ); }

//  F1  = <e > E .
void F1::fun(  )
{ // outgoing calls
  this->get_e()->fun(  ); }

//  E  = <f > F .
void E::fun(  )
{ // outgoing calls
  this->get_f()->fun(  ); }

//  F  = .
void F::fun(  )
{ // prefix class wrappers
 cout << "in F " << endl; }

Rewrite the following programs so that they satisfy the Law of Demeter.


========================================================
// violating the Law of Demeter
// A = <p1> P1.
void A::f1(A* a, B* b) {
  this -> get_p1() -> get_p2() -> r(a,b); }

// satisfying the Law of Demeter
// A = <p1> P1.
void A::f1(A* a, B* b) {
  this -> get_p1() -> f1(a,b); }

// P1 = <p2> P2.
void P1::f1(A* a, B* b) {
  this -> get_p2() -> r(a,b); }
========================================================
========================================================
// violating the Law of Demeter
// A = <p1> P1.
void A::f1(A* a, B* b, C* c, D* d) {
  this -> get_p1() -> r(a,b) -> s(c,d); }

// satisfying the Law of Demeter
// A = <p1> P1.
void A::f1(A* a, B* b, C* c, D* d) {
  this -> f1(this -> get_p1() -> r(a,b), c, d); }

// A = <p1> P1.
void A::f1(R* r, C* c, D* d) {
  r -> s(c,d); }
========================================================