// 7. Proxy êëàñîâå.
//
// Fig. 7.20: implementation.h
// Header file for class Implementation

class Implementation {

public:

   // constructor
   Implementation( int v )  
      : value( v )  // initialize value with v
   { 
      // empty body

   } // end constructor Implementation

   // set value to v
   void setValue( int v )   
   { 
      value = v;  // should validate v

   } // end function setValue

   // return value 
   int getValue() const      
   { 
      return value; 

   } // end function getValue

private:
   int value;

}; // end class Implementation
/****/
// Fig. 7.21: interface.h
// Header file for interface.cpp

class Implementation;     // forward class declaration

class Interface {

public:
   Interface( int );
   void setValue( int );  // same public interface as
   int getValue() const;  // class Implementation
   ~Interface();

private:

   // requires previous forward declaration (line 4)
   Implementation *ptr;   

}; // end class Interface
/****/
// Fig. 7.22: interface.cpp
// Definition of class Interface
#include "interface.h"       // Interface class definition
#include "implementation.h"  // Implementation class definition

// constructor
Interface::Interface( int v ) 
   : ptr ( new Implementation( v ) )  // initialize ptr
{ 
   // empty body

} // end Interface constructor

// call Implementation's setValue function
void Interface::setValue( int v ) 
{ 
   ptr->setValue( v ); 

} // end function setValue

// call Implementation's getValue function
int Interface::getValue() const 
{ 
   return ptr->getValue(); 

} // end function getValue

// destructor
Interface::~Interface() 
{ 
   delete ptr; 

} // end ~Interface destructor
/****/
// Fig. 7.23: fig07_23.cpp
// Hiding a class’s private data with a proxy class.
#include <iostream>

using std::cout;
using std::endl;

#include "interface.h"  // Interface class definition

int main()
{
   Interface i( 5 );
 
   cout << "Interface contains: " << i.getValue() 
        << " before setValue" << endl;

   i.setValue( 10 );

   cout << "Interface contains: " << i.getValue() 
        << " after setValue" << endl;

   return 0;

} // end main