Dear list, while developing I want to use functors for a guard. The state machine compiles well until I added a function call to the FSM which has a template parameter. Then I always got the following error message while compiling it with gcc 4.4.1. SubtractionControllerNew.cpp: In member function 'bool<unnamed>::player_::isCDLoaded::operator()(const EVT&, FSM&, SourceState&, TargetState&)': SubtractionControllerNew.cpp:175: error: expected primary-expression before '>' token SubtractionControllerNew.cpp:175: error: expected primary-expression before ')' token Does anybody know why this happens and how to circumvent it? Kind regards, Sven ---- Example from flags. I have modified the CDLoaded example to present the bug with the following lines: struct isCDLoaded { template <class EVT,class FSM,class SourceState,class TargetState> bool operator()(EVT const& ,FSM& fsm,SourceState& ,TargetState& ) { //return fsm.is_contained(); // this works well return fsm.is_flag_active<CDLoaded>(); // Line 175 } }; Row < Stopped , open_close , Open , none , isCDLoaded >, // Copyright 2010 Christophe Henry // henry UNDERSCORE christophe AT hotmail DOT com // This is an extended version of the state machine available in the boost::mpl library // Distributed under the same license as the original. // Copyright for the original version: // Copyright 2005 David Abrahams and Aleksey Gurtovoy. Distributed // under the Boost Software License, Version 1.0. (See accompanying // file LICENSE_1_0.txt or copy at // http://www.boost.org/LICENSE_1_0.txt) #include <iostream> // back-end #include <boost/msm/back/state_machine.hpp> //front-end #include <boost/msm/front/state_machine_def.hpp> #include <boost/msm/front/functor_row.hpp> #include <boost/msm/front/euml/common.hpp> namespace msm = boost::msm; namespace mpl = boost::mpl; using namespace msm::front; namespace // Concrete FSM implementation { // events struct play {}; struct end_pause {}; struct stop {}; struct pause {}; struct open_close {}; struct NextSong {}; struct PreviousSong {}; // Flags. Allow information about a property of the current state struct PlayingPaused{}; struct CDLoaded {}; struct FirstSongPlaying {}; // A "complicated" event type that carries some data. struct cd_detected { cd_detected(std::string name) : name(name) {} std::string name; }; // front-end: define the FSM structure struct player_ : public msm::front::state_machine_def<player_> { // The list of FSM states struct Empty : public msm::front::state<> { // every (optional) entry/exit methods get the event passed. template <class Event,class FSM> void on_entry(Event const&,FSM& ) {std::cout << "entering: Empty" << std::endl;} template <class Event,class FSM> void on_exit(Event const&,FSM& ) {std::cout << "leaving: Empty" << std::endl;} }; struct Open : public msm::front::state<> { typedef mpl::vector1<CDLoaded> flag_list; template <class Event,class FSM> void on_entry(Event const&,FSM& ) {std::cout << "entering: Open" << std::endl;} template <class Event,class FSM> void on_exit(Event const&,FSM& ) {std::cout << "leaving: Open" << std::endl;} }; struct Stopped : public msm::front::state<> { // when stopped, the CD is loaded typedef mpl::vector1<CDLoaded> flag_list; template <class Event,class FSM> void on_entry(Event const&,FSM& ) {std::cout << "entering: Stopped" << std::endl;} template <class Event,class FSM> void on_exit(Event const&,FSM& ) {std::cout << "leaving: Stopped" << std::endl;} }; // the player state machine contains a state which is himself a state machine // as you see, no need to declare it anywhere so Playing can be developed separately // by another team in another module. For simplicity I just declare it inside player struct Playing_ : public msm::front::state_machine_def<Playing_> { // when playing, the CD is loaded and we are in either pause or playing (duh) typedef mpl::vector2<PlayingPaused,CDLoaded> flag_list; template <class Event,class FSM> void on_entry(Event const&,FSM& ) {std::cout << "entering: Playing" << std::endl;} template <class Event,class FSM> void on_exit(Event const&,FSM& ) {std::cout << "leaving: Playing" << std::endl;} // The list of FSM states struct Song1 : public msm::front::state<> { typedef mpl::vector1<FirstSongPlaying> flag_list; template <class Event,class FSM> void on_entry(Event const&,FSM& ) {std::cout << "starting: First song" << std::endl;} template <class Event,class FSM> void on_exit(Event const&,FSM& ) {std::cout << "finishing: First Song" << std::endl;} }; struct Song2 : public msm::front::state<> { template <class Event,class FSM> void on_entry(Event const&,FSM& ) {std::cout << "starting: Second song" << std::endl;} template <class Event,class FSM> void on_exit(Event const&,FSM& ) {std::cout << "finishing: Second Song" << std::endl;} }; struct Song3 : public msm::front::state<> { template <class Event,class FSM> void on_entry(Event const&,FSM& ) {std::cout << "starting: Third song" << std::endl;} template <class Event,class FSM> void on_exit(Event const&,FSM& ) {std::cout << "finishing: Third Song" << std::endl;} }; // the initial state. Must be defined typedef Song1 initial_state; // transition actions void start_next_song(NextSong const&) { std::cout << "Playing::start_next_song\n"; } void start_prev_song(PreviousSong const&) { std::cout << "Playing::start_prev_song\n"; } // guard conditions typedef Playing_ pl; // makes transition table cleaner // Transition table for Playing struct transition_table : mpl::vector4< // Start Event Next Action Guard // +---------+-------------+---------+---------------------+--------------- -------+ a_row < Song1 , NextSong , Song2 , &pl::start_next_song >, a_row < Song2 , PreviousSong, Song1 , &pl::start_prev_song >, a_row < Song2 , NextSong , Song3 , &pl::start_next_song >, a_row < Song3 , PreviousSong, Song2 , &pl::start_prev_song > // +---------+-------------+---------+---------------------+--------------- -------+ > {}; // Replaces the default no-transition response. template <class FSM,class Event> void no_transition(Event const& e, FSM&,int state) { std::cout << "no transition from state " << state << " on event " << typeid(e).name() << std::endl; } }; // back-end typedef msm::back::state_machine<Playing_> Playing; // state not defining any entry or exit struct Paused : public msm::front::state<> { typedef mpl::vector2<PlayingPaused,CDLoaded> flag_list; }; // the initial state of the player SM. Must be defined typedef Empty initial_state; // transition actions void start_playback(play const&) { std::cout << "player::start_playback\n"; } void open_drawer(open_close const&) { std::cout << "player::open_drawer\n"; } void close_drawer(open_close const&) { std::cout << "player::close_drawer\n"; } void store_cd_info(cd_detected const& ) {std::cout << "player::store_cd_info\n";} void stop_playback(stop const&) { std::cout << "player::stop_playback\n"; } void pause_playback(pause const&) { std::cout << "player::pause_playback\n"; } void resume_playback(end_pause const&) { std::cout << "player::resume_playback\n"; } void stop_and_open(open_close const&) { std::cout << "player::stop_and_open\n"; } void stopped_again(stop const&){std::cout << "player::stopped_again\n";} // guard conditions struct isCDLoaded { template <class EVT,class FSM,class SourceState,class TargetState> bool operator()(EVT const& ,FSM& fsm,SourceState& ,TargetState& ) { //return fsm.is_contained(); return fsm.is_flag_active<CDLoaded>(); } }; typedef player_ p; // makes transition table cleaner // Transition table for player struct transition_table : mpl::vector< // Start Event Next Action Guard // +---------+-------------+---------+---------------------+--------------- -------+ a_row < Stopped , play , Playing , &p::start_playback

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Row < Stopped , open_close , Open , none , isCDLoaded >, a_row < Stopped , stop , Stopped , &p::stopped_again

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// +---------+-------------+---------+---------------------+--------------- -------+ a_row < Open , open_close , Empty , &p::close_drawer

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// +---------+-------------+---------+---------------------+--------------- -------+ a_row < Empty , open_close , Open , &p::open_drawer

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a_row < Empty , cd_detected , Stopped , &p::store_cd_info

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// +---------+-------------+---------+---------------------+--------------- -------+ a_row < Playing , stop , Stopped , &p::stop_playback

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a_row < Playing , pause , Paused , &p::pause_playback

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a_row < Playing , open_close , Open , &p::stop_and_open

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// +---------+-------------+---------+---------------------+--------------- -------+ a_row < Paused , end_pause , Playing , &p::resume_playback >, a_row < Paused , stop , Stopped , &p::stop_playback

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a_row < Paused , open_close , Open , &p::stop_and_open

// +---------+-------------+---------+---------------------+--------------- -------+ > {}; // Replaces the default no-transition response. template <class FSM,class Event> void no_transition(Event const& e, FSM&,int state) { std::cout << "no transition from state " << state << " on event " << typeid(e).name() << std::endl; } }; // Pick a back-end typedef msm::back::state_machine<player_> player; // // Testing utilities. // static char const* const state_names[] = { "Stopped", "Open", "Empty", "Playing", "Paused" }; void pstate(player const& p) { std::cout << " -> " << state_names[p.current_state()[0]] << std::endl; } void test() { player p; // needed to start the highest-level SM. This will call on_entry and mark the start of the SM p.start(); // tests some flags std::cout << "CDLoaded active:" << std::boolalpha << p.is_flag_active<CDLoaded>() << std::endl; //=> false (no CD yet) // go to Open, call on_exit on Empty, then action, then on_entry on Open p.process_event(open_close()); pstate(p); p.process_event(open_close()); pstate(p); p.process_event(cd_detected("louie, louie")); p.process_event(play()); // at this point, Play is active std::cout << "PlayingPaused active:" << std::boolalpha << p.is_flag_active<PlayingPaused>() << std::endl;//=> true std::cout << "FirstSong active:" << std::boolalpha << p.is_flag_active<FirstSongPlaying>() << std::endl;//=> true // make transition happen inside it. Player has no idea about this event but it's ok. p.process_event(NextSong());pstate(p); //2nd song active p.process_event(NextSong());pstate(p);//3rd song active p.process_event(PreviousSong());pstate(p);//2nd song active std::cout << "FirstSong active:" << std::boolalpha << p.is_flag_active<FirstSongPlaying>() << std::endl;//=> false std::cout << "PlayingPaused active:" << std::boolalpha << p.is_flag_active<PlayingPaused>() << std::endl;//=> true p.process_event(pause()); pstate(p); std::cout << "PlayingPaused active:" << std::boolalpha << p.is_flag_active<PlayingPaused>() << std::endl;//=> true // go back to Playing // as you see, it starts back from the original state p.process_event(end_pause()); pstate(p); p.process_event(pause()); pstate(p); p.process_event(stop()); pstate(p); std::cout << "PlayingPaused active:" << std::boolalpha << p.is_flag_active<PlayingPaused>() << std::endl;//=> false std::cout << "CDLoaded active:" << std::boolalpha << p.is_flag_active<CDLoaded>() << std::endl;//=> true // event leading to the same state p.process_event(stop()); pstate(p); } } int main() { test(); return 0; }