#include <boost/signal.hpp> 

struct event_handler 
{ 
	void operator()() 
	{ 
	} 
}; 

int main() 
{ 
	event_handler eh; 

	boost::signal<void ()> sig; 
	sig.connect(eh); 
	sig.disconnect(eh);		// VS2005 SP1 error C2678: binary '==' : no operator found which takes a left-hand operand of type 'const event_handler' (or there is no acceptable conversion) 
}