static factory...

[superbonzo]

This has become silly

It's your responsability to explain clearly what's your problem. Your code it's not clear and it's full of inconcistencies that make very hard to understand exactly what's your real intent.

As far as I could read from your code snippets you have two class hyerarchies P and D, a mechanism describing a set of fixed connections between pairs of P's and D's, a function (update_p_msg) issuing a message to some P and a function (process) notifing the message to the correspondingly connected D's. Am I right ?

If this is the case,

typedef int			Message;
typedef boost::shared_ptr<P>	PPtr;
typedef boost::shared_ptr<D>	DPtr;
typedef std::pair<PPtr,DPtr>	PDConn;

void Process( P& p, Message msg );
void Process( D& d, Message msg );

class ProcessConnection: std::unary_function<const PDConn&,void>
{
public:
	ProcessConnection( Message msg )
		: msg_(msg) {}


	void operator()( const PDConn& connection) const
	{
		Process( *connection.first, msg_ );
		Process( *connection.second, msg_ );
	}
	
private:
	Message	msg_;
};

int main()
{
	std::vector<PPtr>		vector_of_Ps;
	std::vector<DPtr>		vector_of_Ds;
	std::multi_map<PPtr,DPtr>	connections;

	// pupulate vectors

	vector_of_Ps.push_back( ... );
	vector_of_Ds.push_back( ... );

	// pupulate connections

	connections.insert( PDConn( vector_of_Ps.front(), vector_of_Ds.back() ) );

	// "send" a message

	Message	some_message = 1;

	std::for_each( connections.begin(), connections.end(),
		ProcessConnection( some_message ) );
}

ps.: I've not compiled nor tested the code...