Re: [Boost-users] [MSM] How to use is_flag_active inside on_entry ?

Subject: Re: [Boost-users] [MSM] How to use is_flag_active inside on_entry ?
From: Gábor Márton (gabor.marton_at_[hidden])
Date: 2011-08-27 14:44:20

>> Hi,
>>
>> I would like to use is_flag_active<SomeFlag>() function inside one of 
>> my state's on_entry template function:
>> struct StBladeDown : public msm::front::state<> { template<class 
>> Event, class FSM> void on_entry(Event const& event, FSM& fsm) {
>> if(fsm.is_flag_active<FlagMaster>()) { // ERROR // doSomeThing(); } } 
>> }; However I got the following compile error:
>> StOk.hpp: In member function 'void
>> mr::mrd::amfo::StOk_::StBladeDown::on_entry(const Event&, FSM&)':
>> StOk.hpp:78: error: expected primary-expression before '>' token
>> StOk.hpp:78: error: expected primary-expression before ')' token
>>
>> However outside of the state machine, I mean if I first declare a 
>> state machine, I can use the is_flag_active:
>> StAMFODirector backEnd;
>> backEnd.start();
>> processEvent(backEnd,EvBladeDown());
>> processEvent(backEnd,EvMaster());
>> if(backEnd.is_flag_active<FlagMaster>()){ // OK _LOG_DEBUG("Flag 
>> Master active"); }
>>
>> If I use the front_end's is_flag_ I get compiler error again (no such 
>> function in msm::back::state_machine).
>>
>> Any idea how to use is_flag_active together with on_entry? Or if it is 
>> not possible are there any alternatives?
>>
>> Thanks for any help,
>> Gabor
>
> Hi Gabor,
> 
> welcome to gcc's readable error messages ;-) I really have to make this clear in the doc. Sorry about it.
> 
> on_entry is a template function so you need to add a template keyword.
> Try:
>  struct StBladeDown : public msm::front::state<> {  template<class Event, class FSM>  void on_entry(Event const& event, FSM& fsm) {  if(fsm.template is_flag_active<FlagMaster>()) {  // doSomeThing();  }  }  };
> 
> HTH,
> Christophe

Hi Christophe,

It is great to hear the answer from the library author!

Many thanks,
Gabor