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Posted 21 May 2005

A policy based reference counting implementation for compound objects

, 26 May 2005 CPOL
Reference counting smart pointers and handles of various flavours.
//	c0.cpp

#include "stdafx.h"

#include "stdx/msgrouter.hpp"

/// stdx::smart testing
//	run in debug mode an read messagess on the output window

using namespace GE_;

//struct A and C are nodes and arcs of a graph

struct C; //forwarded

struct A: //A is a graph node and also a hierarchy node
	public stdx::graph::node<A, C>, 
	public stdx::hierarchy_node<A>
	int a; //an ID
		static int n(0); a = ++n;  //count and save
		STRACE(trc, 1, ("Created A #%d at %p\n", a, this));
	virtual ~A() 
	{	STRACE(trc, 1, ("Deleted A #%d at %p\n", a, this)); }

	void on_data(int& i) 
		STRACE(t,1,("Broadcasting %d to Node #%d\n", i, a));

	void on_lastrelease() //disambiguate
		stdx::graph::node<A, C>::on_lastrelease();

struct B: public A
	B() { a += 100; } //B will have 100+xx as ID

struct C:
	stdx::graph::arc<C, A>
	int c;
		static int n(0); c = ++n; //same trick as for A
		STRACE(t,1,("Creating C #%d at %p\n",c,this));
	virtual ~C()
	{	STRACE(t,1,("Deleting C #%d at %p\n",c,this)); }


int main()
	STRACE(trc, 0, ("c0 main\n"));
	static const int n=25;
	A::ptr pA; pA.New(); //the capostipit for everything
	for(size_t i=0; i<n; i++) 
		//place n nodes into the capostipit. One B every three A
		if(! (i%4))
		{	B* p; stdx::New(p); pA->set_last(p); }
		{	A* p; stdx::New(p); pA->set_last(p); }
		int m = n-1;
		C::Arc_p p; p.New(); //create an arc
		int frm = rand()*m/RAND_MAX;  //generate two random numbers from 0 to n-1
		int to = rand()*m/RAND_MAX;
		p->link(pA->get_child(frm), pA->get_child(to)); //link the nodes having that indexes

	//do a simple graph visit
	for(A::ptr pN = pA->get_first(); pN; pN = pN->get_next()) 
	{//loop all the nodes
		for(A::arc_iterator a=pN->begin_arcto(); a!=pN->end_arcto(); a++)
		{//loop all outgoing arcs
			A::ptr pTo = a->get_to(); //get arc destination
			int idfrom = pN->a; //node ID
			int idto = (pTo)? pTo->a: 0; //destination ID
			int idarc = a->c; //arc ID
			STRACE(t,2,("Node #%d, linked to Node #%d by Arc #%d\n", idfrom,idto,idarc));

	//try broadcasting from the first node
	int count(0); A* pa(pA->get_first());
	for(; pa; pa=pa->get_next())
		STRACE(t,1,("BackBroadcast from #%d\n", pa->a));
		stdx::graph::backroute_linked(++count, *pa, std::mem_fun(&A::on_data));
		SRETRACE(t,("Broadcast from #%d\n", pa->a));
		stdx::graph::route_linked(count, *pa, std::mem_fun(&A::on_data));

	return 0;

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About the Author

Emilio Garavaglia
Italy Italy
Born and living in Milan (Italy), I'm an engineer in electronics actually working in the ICT department of an important oil/gas & energy company as responsible for planning and engineering of ICT infrastructures.
Interested in programming since the '70s, today I still define architectures for the ICT, deploying dedicated specific client application for engineering purposes, working with C++, MFC, STL, and recently also C# and D.

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