Hi Christophe, thanks for the reply. The reason I want to extend the backend is that I need to maintain a separate event queue (a job queue). In reality, "test()" is a function template, so I cannot use virtual functions. If I implement this function template in the frontend, I need to static_cast to the backend, which I try to avoid: struct fsm_ : public boost::msm::front::state_machine_def { typedef msmb::state_machine BackMachine; template <typename EventType> void enqueue_job(const EventType& evt) { job_queue.push( std::bind(&BackMachine::template process_event<EventType>, static_cast(this), evt) ); } // ... }; Is there any third option? Bye, Manuel 2014-09-07 21:42 GMT+02:00 :

Hi,

...

When compiling the attached example, I get this error message

*>error: ‘class boost::msm::back::state_machine’ has no member named ‘test’*

...

How can I "inject" extended_back_machine as the type being passed as

"FSM" to the state? The argument passed to on_entry is not extended_back_machine because MSM does not know about it. You can either:

- implement test() within the fsm_ front-end - provide a virtual, empty implemented test() within the front end and let the compiler find out itself about the overriden one: virtual void test(){}

HTH, Christophe

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