This thread is for discussions of Circular Referencing to COM Objects.

very interesting and usefull trick. (I should have thought about it myself)

I struggled for a long time with my app hanging after it quits.  It turned out to be a circular reference in the (approximately) 180 000 objects.

Thnx for the great explanation and work-around.  Everything going smoothly again.

igitur

Glad it helped.

I have a project with Splitter controls that require references to pairs of controls that are proportionally resized by the user.
The application GPF's (occasionally) upon termination. If run inside a browser, it causes an error report and the browser stays in memory.
I realize that setting the controls reference to Nothing during the Usercontrol_Terminate event would solve the problem, but your article explains why this was not happening. So that is good.
Your solution is intriguing, but I would like to ask you if another solution might work.
How about we reduce the refrence count on the objects in the Initialize routine? Like this:

Private Sub UserControl_Initialize()
   Set Splitter1.LeftCtl = LeftThing
   Set Splitter1.RightCtl = RightThing

   ReduceRefrenceCountByOne LeftThing
   ReduceRefrenceCountByOne RightThing
End Sub

Now the Controls will be come out of memory as we really want when the parent control terminates. Incidentally, their UserControl_Terminate events will fire correctly too.

Perhaps you have written the code to do the evil reference count manipulation?

What do you think?

G.

There is no secret as to how you decrease the reference count of a COM object.  All you have to do is call the Release method of the IUnknown interface.  But VB will hide this.  However, you can cheat by creating or using a type library that does define the IUknown interface.  Then you could just do something like this:
Code:

Private Sub UserControl_Initialize()

dim oObject as IUnknown

  Set Splitter1.LeftCtl = LeftThing
  Set Splitter1.RightCtl = RightThing

  set oObject = LeftThing
  oObject.Release
  set oObject = Nothing
  set oObject = RightThing
  oObject.Release
  set oObject = Nothing
End Sub

That should take care of it.  However, this method is somewhat cumbersome and can be easily avoided by soft referencing.  I say go with soft referencing.

Great tutorial.This will definitely change the way i look up on these Matters..