Re: [boost] [MSM] Compile-time error using SubMachines and events that carries some data

23 May 2013

      Thanks Takatoshi,

Seemed odd to me that MSM instantiate a State using a "wrong" Event.
I thought I was doing something wrong.

The enable_if solution works perfect. :)

Thanks and regards,
Fernando Pelliccioni

On Thu, May 23, 2013 at 3:53 PM, Takatoshi Kondo  wrote:
...
Hi Fernando,
Boost.Msm instansiates on_entry member function with various events even if
your transition never happen. Hence you can't assume that event handler's
template palameta "Event" is always the event you set on your transition
table.
IIUC, this is a MSM spacification.
To solve this problem, you can use SFINAE as follows:
struct StaringGame : public msm::front::state<>
            {
                template 
                void on_entry(Event const& event, FSM& fsm, typename
boost::
enable_if >::type* = 0 )
                {
                    std::cout << "entering: StaringGame" << std::endl;
                    std::cout << "event.element(): " << event.element() <<
std::endl;
                    std::cout << "event typeid: " << typeid(event).name()
 << std::endl;
                }
                template 
                void on_entry(Event const& event, FSM& fsm, typename
boost::
disable_if >::type* = 0 )
                {
                }
            };
struct StartTurn: public msm::front::state<>
            {
                template 
                void on_entry(Event const& event, FSM& fsm, typename
boost::
enable_if >::type* = 0 )
                {
                    std::cout << "entering: StartTurn" << std::endl;
                    std::cout << "event.element(): " << event.element() <<
std::endl;
                    std::cout << "event typeid: " << typeid(event).name()
 << std::endl;
                }
                template 
                void on_entry(Event const& event, FSM& fsm, typename
boost::
disable_if >::type* = 0 )
                {
                }
            };
Could you try it?
Takatoshi Kondo
On Thu, May 23, 2013 at 11:05 AM, Fernando Pelliccioni <
fpelliccioni@gmail.com> wrote:
...
Hi,
I have a Main State Machine (state_machine_) and two SubMachines.
I want to start the first SubMachine and when it finished I want to start
the second SubMachine.
Here is the code.
http://pastebin.com/sBdS1wvJ
I have a compile-time error on some States of the second SubMachine.
error: no member named 'element' in 'exit_introduction'
                    std::cout << "event.element(): " << event.element()
<<
std::endl;
                                                        ~~~~~ ^
This is on state "StaringGame" and according the Transition Table of
GameSM, only the event "character_selected" is used.
I don't know why is trying to use the event "exit_introduction".
Is this a bug of MSM?
Am I doing something wrong?
Thanks and regards,
Fernando Pelliccioni.
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