Std::vector is initialized to garbage. Weird behavior. Any ideas on what's up?

Question

My class has this member.

  std::vector<AvaWrapper> m_controls;

In my constructor I call

  m_controls.clear()

Then I call a member function that does m_controls.clear() again but it blows up with an assert. The debugger shows that m_controls has a half million or more entries though none of them are valid cause the debugger shows "Error: expression cannot be evaluated" when I expand the tree. So, my intuition is that the class is not created correctly cause this code did work but I later derived a class from this class and I call new() to create the parent. In it's new role as a base class it's blowing up. The this pointer however shows all the other member variables have valid data so my hunch is wrong. The constructor is getting called too. Any ideas? Thanks.

UPDATE2:

Train::Train() : SpriteWindowFrame(200)
{
  s_mutexProtectingTheGlobalData = new wxMutex();
  m_window_rect = NULL;
  m_thread = NULL;
  m_ok = false;
  m_accumulate_timer = new wxTimer();
  m_accumulate_timer->SetOwner(this, ACCUMULATE_TIMER_ID);

  m_autohide_timer = new wxTimer();
  m_autohide_timer->SetOwner(this, AUTOHIDE_TIMER_ID);

  m_autohide = false;
  m_autohide_period = 5000;
  m_controls.clear();
}

UPDATE:

//This version works.
SpaceInit::SpaceInit()
{
  //Use INI config store. If you need something else, just
  //create the appropriate object.
  m_config_store = new IniConfigStore();

  //Start up config. 
  Init(); 

  m_t = new Trains();
  return;
}

SpaceInit::~SpaceInit()
{
  wxDELETE(m_config_store);
  return;
}

I can do this: m_t->SomeMemberFunctionThatManipulatesVector()

and it works.

This one does not

SpaceInit::SpaceInit():Trains()
{
  //Use INI config store. If you need something else, just
  //create the appropriate object.
  m_config_store = new IniConfigStore();

  //Start up config. 
  Init(); 
  return;
}

I can't do: SomeMemberFunctionThatManipulatesVector()

blows up on vector.

I've just noticed that the this pointer really is messed up inside the Train() default consturctor. I thought it wasn't but it is. The Trains constructor runs but everything is trashed.

My Trains constructor code is run of the mill. Just initialize things, new a couple things, etc. The SpaceInit is created with SpaceInit* t = new SpaceInit(); Train is a derived class so maybe that has something to do with it?

Answer 1

There's a problem with this statement:

I later derived a class from this class and I call new() to create the parent.

When you derive from a class, you do not call new() to create a parent. The parent constructor is already called before the first line of the child constructor is run.

I suspect that your problem might be around this area. Perhaps you could show us the code where this is happening.

Answer 2

Since you seem to have RAW pointers (hard to tell as we don't have the definition of SpaceInit). Have you defined the copy constructor and assignment operator. If not you could potentially be accessing destroyed objects which would lead to undefined behavior included overwriting other members.

Answer 3

I'm with @andrew-shepherd. Since you got different results when you changed initialization order of the class Trains, I strongly recommend you check all the base and derived classes about the "initialization list."

If you were not allowed to show the specific code snippet, please at least ensure all data member of each class were on the initialization list, not in the ctor.

Answer 4

Hello

I'm just geuessing that the Init method is virtual. The rule no. 1 is you shall not call virtual methods from ctor because object may not be initialized properly.

Regards