I wrote a simple code. source file: #include <boost/statechart/event.hpp> #include <boost/statechart/transition.hpp> #include <boost/statechart/simple_state.hpp> #include <boost/statechart/state.hpp> #include <boost/statechart/state_machine.hpp> #include <boost/statechart/custom_reaction.hpp> #include <boost/shared_ptr.hpp> #include <boost/weak_ptr.hpp> #include <boost/mpl/list.hpp> #include <iostream> #include <string> using namespace std; namespace sc=boost::statechart; namespace mpl=boost::mpl; struct EvtEat:sc::event<EvtEat>{}; struct EvtStop:sc::event<EvtStop>{}; struct Eating; struct Idle; class Human:public sc::state_machine< Human, Idle > { public: void show(void) { cout<<__FUNCTION__<<endl; } }; struct Idle:sc::state< Idle, Human > { Idle(my_context ctx):my_base(ctx) { context<Human>().show(); //ok }; ~Idle(void) { context<Human>().show(); //assert failed }; }; struct Eating:sc::state< Eating, Human > { Eating(my_context ctx):my_base(ctx) { }; ~Eating(void) { context<Human>(); } }; int main(int argc, char* argv[]) { Human human; human.initiate(); return 0; } /* In debug mode.It output Human::show Assertion failed: dynamic_cast<Target>(x) == x, file p:\programme\libs\boost\include\boost-1_35\boost\cast.hpp, line 97 */ Why does it assert failed and how to modify the source? Thank you.