Member value changes between successive calls of the same function

I have a CognitiveEntity class, defined this way:

class CognitiveEntity : public Object
{
public:
  CognitiveEntity (FuzzyCognitiveMap fcm, SystemState s);
  ~CognitiveEntity ();

  template <typename T> void RegisterChange (std::string context, T value);

  bool operator!= (const CognitiveEntity& rhs) const;

private:
  FuzzyCognitiveMap m_fuzzyCognitiveMap;
  SystemState       m_systemState;

  std::vector <SystemState> RunFuzzyCognitiveMap ();
};

As shown, a CognitiveEntity has a SystemState object, which in turn has a vector of Concept objects (only the most relevant lines are shown):

cl开发者_StackOverflow中文版ass SystemState
{
public:
  SystemState ();
  ~SystemState ();

  void       AddConcept (Concept c) { m_L.push_back(c); }
  std::vector <Concept> m_L;
};

Inside the CognitiveEntity::RegisterChange, I mark a Concept as a potential cause (by calling Concept::IsPotentialCause (bool) which merely sets a private member with the value passed):

template <typename T>
void
CognitiveEntity::RegisterChange (std::string context, T value)
{
  std::string name = context.substr(context.find_last_of ("/") +1);
  int pos = m_systemState.FindConcept(name);
  if (pos > -1)
  {
    int intValue = value ? 1 : 0;
    m_systemState.m_L[pos].SetConceptValue (intValue, false);

    if (m_systemState.m_L[pos].CheckVariation ())
    {
      m_systemState.m_L[pos].IsPotentialCause (true); // Mark this concept as a potential cause

      for (int cause = 0; cause < m_systemState.GetSize (); cause++)
      {
        if ( (cause != pos) && (m_systemState.m_L[cause].MayBeCause ()))
        {
          m_fuzzyCognitiveMap.UpdateFuzzyCognitiveMapEntry (cause, pos, m_systemState);
          m_systemState.m_L[cause].IsPotentialCause (false);
        }
      }
    }
  }

}

What happens is that as soon as RegisterChange is called another time, the Concept that was marked as potential cause, is marked no more. I tried running gdb and I am sure that that member is not set elsewhere.

I'm not sure if this little information is enough for you to give me some hints about such a behavior (I didn't want to flood the post with the code of both SystemState and Concept classes).

Regards, Jir

---

If this was a multi-threaded system, I'd say it sounds like a classic case of shared, mutable state that wasn't properly synchronized.

If you don't have a multi-threaded situation, I'd say set a watch on that variable and see what changes it.

---

Turns out the problem lied in how the code was called from within the network simulator (the code was meant to be used in the "ns-3" network simulator).

So, the problem wasn't even in the code I posted, and yet you managed to help me find the solution: thanks to the suggestions you gave me, I prepared a standalone version of the code and I watched the variable.

The problem was how I was passing the object. Specifically, instead of passing around the object by reference (as I thought I was doing) I should have used smart pointers.

Thank you all for the great insights! (and sorry for the mess... next time I'll be more accurate!)