// 8_4.cpp : Defines the entry point for the console application.The army class is decoupled from the map class and vice versa. We need to tie armies to maps so, we need access to the (externally defined) map and army objects in this class. This can be done in the gamedata class and to make this possible, include references to both map and army objects.
//
#include "stdafx.h"
class gamedata; // make available to game and map classes
class map {
int mapsize;
public :
map( int newmapsize) { mapsize=newmapsize;};
};
class army {
int armysize;
public :
army( int newarmysize) { armysize = newarmysize;};
};
class game {
map & m;
army & a;
public :
gamedata( map & amap, army & anarmy) ;
};
gamedata::gamedata( map & amap, army & anarmy) : m(amap), a(anarmy) {}
int main(int argc, char* argv[])
{
map amap(1) ;
army anarmy(10) ;
gamedata g(amap,anarmy) ;
return 0;
}
In a constructor, you cannot assign a value to a reference except when it is created, ie initialized. The initializer lists provides a way to do this before the body of the constructor is called. In example 8_4, both amap and anarmy exist elsewhere before the gamedata constructor is called.
On the next Page : More about decoupling classes
