Question

template <class EventType>
class IEvent;

class IEventable;

typedef boost::function<void (IEventable&, IEvent&)> behaviorRef;

What is the right way for passing template class IEvent into boost function? With this code I get:
error: functional cast expression list treated as compound expression
error: template argument 1 is invalid
error: invalid type in declaration before ‘;’ token

Answer 1

boost::function needs a type, so you cannot pass it a template‘s name, it has to be a template instance. So either use a specific instance

typedef boost::function<void (IEventable&, IEvent<SomeEventType>&)> behaviorRef;

or put the whole thing itself into a template:

template< typename EventType >
struct foo {
  typedef boost::function<void (IEventable&, IEvent<EventType >&)> behaviorRef;
};