[Boost-users] [StateChart] Accessing machine and state members from within state constructor

10 Jul 2012

      Hello,

I'd like to outsource some common functionality into a base state which
needs to access some member variables from the state machine or from its
direct context. I've managed to do exactly this in the constructor of
the inherited class but not inside the constructor of the base class. I
believe I am missing some bits here.

Thanks in advance
-Andre

Code:
#include <boost/statechart/event.hpp>
#include <boost/statechart/state_machine.hpp>
#include <boost/statechart/state.hpp>
#include <boost/statechart/simple_state.hpp>
#include <boost/statechart/transition.hpp>
#include <boost/statechart/custom_reaction.hpp>
#include <iostream>

namespace sc = boost::statechart;

// event definition
struct EvReset : sc::event< EvReset > {};

// forward definition
struct Active; // starting state
struct State1;

// define FSM
struct TestFsm : sc::state_machine< TestFsm, Active >
{
    TestFsm()
    {
        std::cout << "Start TestFsm.\n";
        fsmValue = 0;
        std::cout << "value: " << fsmValue << std::endl;
    }
    ~TestFsm() { std::cout << "Shut down TestFsm.\n"; }

public:
    int fsmValue;
};

struct Active : sc::state< Active, TestFsm, State1 >
{
    Active(my_context ctx) : my_base( ctx )
    {
        std::cout << "Start Active state!\n";
        outermost_context().fsmValue++;
        stateValue = 0;
        std::cout << "value: " << outermost_context().fsmValue << std::endl;
    }
    ~Active() { std::cout << "Leave and desctruct Active state!\n"; }

public:
    int stateValue;

    typedef sc::transition< EvReset, Active > reactions;

};

template< class MostDerived, class Context >
struct StateBase : sc::state< MostDerived, Context>
{
    typedef sc::state< MostDerived, Context> base_type;
    typedef typename base_type::my_context my_context;
    typedef StateBase my_base;

    StateBase( my_context ctx ) : base_type( ctx )
    {
        std::cout << "StateBase cst" << std::endl;
        // critical section
        outermost_context().fsmValue++; // access member of FSM
(outermost context)
        ctx().stateValue++; // access member in direct context
    }
};

struct State1 : StateBase< State1, Active >
{
    State1(my_context ctx) : my_base( ctx )
    {
        std::cout << "State1 cst" << std::endl;
        outermost_context().fsmValue++;
        std::cout << "value: " << outermost_context().fsmValue << std::endl;
    };
    ~State1() {};
};

int main()
{
    TestFsm myFSM;
    myFSM.initiate();
    return 0;
}

[Boost-users] [StateChart] Accessing machine and state members from within state constructor

Andre Puschmann