29 The Power of Inheritance and Polymorphism

Inheritance and Polymorphism 1042WindowRep.h Geom.hD.hDungeon.h Ditem.hmain.cpDitem.cpGeom.cpDungeon.cp WindowRep.cpD.cpmain.oDitem.oGeom.oDungeon.o WindowRep.oD.oFigure 29.8Module structure for Dungeon game example.The files D.h and D.cp contain the DynamicArray code defined in Chapter 21.The Geom files have the definition of the simple Pt class. The WindowRep filescontain WindowRep, Window and its subclasses. DItem.h and DItem.cp contain thedeclaration and definition of the classes in the DungeonItem hierarchy while theDungeon files contain class Dungeon.An outline for main() has already been given; function Terminate(), whichprints an appropriate "you won" or "you lost" message, is trivial.29.3.1 Windows classesThere are two aspects to class WindowRep: its "singleton" nature, and itsinteractions with a cursor addressable screen.The constructor is private. WindowRep objects cannot be created by client code(we only want one, so we don't want to allow arbitrary creation). Clients (like thecode of class Dungeon) always access the unique WindowRep object through thestatic member function Instance().WindowRep *WindowRep::Instance(){if(sWindowRep == NULL)sWindowRep = new WindowRep;