I'm now using Row and Defer functor I have now an other problem whit the :

void defer_event(Event const& e) { // to call this function, you need either a state with a deferred_events typedef // or that the fsm provides the activate_deferred_events typedef BOOST_MPL_ASSERT(( has_fsm_deferred_events<library_sm> )); execute_return (library_sm::*pf) (Event const& evt)= &library_sm::process_event; Event temp (e); ::boost::function<execute_return ()> f= ::boost::bind(pf, this,temp); post_deferred_event(f); }

actually it tries to instantiate the base class ( Event temp (e); ) but in my case the base class is an abstract class -> compiler error; and after deferring I want to dispatch the original derived event not the copy constructed base class instance of the event.

What you get is a slicing. The Defer functor works like any action, meaning that the type of the event is encoded in the transition. If you consider a transition: a_row < Stopped , play , Playing , &p::start_playback > and an action: void start_playback(play const&) The type of the event in the action is the one defined in the transition. So what defer_event gets (from Defer) is the type defined in the transition, in your case the base event. It's harder to spot than a vector<base> but about the same. A solution would be to have msm's process_event reinterpret_cast action signature. I will take it into my feature list but probably not at the top as I consider the feature as only nice to have. In the meantime, I, like Juraj, would also suggest you to pimpl your data (with or without a shared_ptr) or define one entry inside deferred_events for every derived event. Regards, Christophe