/*

OUTPUT
------

Creating P: 
Making a polymorph...
Creating polymorph bits

* Something hijacks the polymorph factory *

Creating Q: 
Making a something...
Creating polymorph bits
Creating something bits

Destroying P: 
Destroying polymorph bits
Done :|
Destroying Q: 
Destroying something bits
Destroying polymorph bits
Done :|

*/


#include <cstdio>

class CPolymorph
{
	public:
		
		virtual ~CPolymorph ()
		{
			puts ("Destroying polymorph bits");
		};	
		
		static CPolymorph* create ()
		{
			return (CPolymorph*) CPolymorph::finalConstructor();
		};
		
	protected:
	
		/* Prevent direct initiation */
		CPolymorph ()
		{
			puts("Creating polymorph bits");
		};
		
		/* Prevent copy construction and reference assignment */
		CPolymorph (const CPolymorph&);
		CPolymorph& operator= (const CPolymorph&);
		
		/* static constructor */
		static void* getBaseInterface ()
		{
			puts ("Making a polymorph...");
			return new CPolymorph();
		};
		
		/* virtual constructor pointer */
		static void* (*finalConstructor)();
};

void* (*CPolymorph::finalConstructor)() = &CPolymorph::getBaseInterface;

class CSomething : CPolymorph
{
	public:
	
		CSomething ()
		{
			puts ("Creating something bits");
		};		
	
		~CSomething ()
		{
			puts ("Destroying something bits");
		};
		
		static 
		void replaceBase()
		{
			CPolymorph::finalConstructor = &CSomething::getBaseInterface;
		};
	
	protected:
	
		static void* getBaseInterface()
		{
			puts ("Making a something...");
			return static_cast<CPolymorph*> (new CSomething());
		};
};

int main (int argc, char** argv)
{
	puts ("Creating P: ");
	CPolymorph* p = CPolymorph::create ();
	
	puts ("\n* Something hijacks the polymorph factory *");
	CSomething::replaceBase();
	
	puts ("\nCreating Q: ");
	CPolymorph* q = CPolymorph::create ();
	
	puts ("\nDestroying P: ");
	delete p;
	puts ("Done :|");
	
	puts ("Destroying Q: ");
	delete q;
	puts ("Done :|");
}