Re: Derived destructor not being called

From:
"Alexander Grigoriev" <alegr@earthlink.net>
Newsgroups:
microsoft.public.vc.language
Date:
Mon, 1 May 2006 07:08:26 -0700
Message-ID:
<eqLO6iSbGHA.1196@TK2MSFTNGP03.phx.gbl>
In addition to other comments, it's WRONG to use reinterpret_cast to cast
between class pointers. It won't do any pointer adjustment.

<stanley_r_eisenberg@raytheon.com> wrote in message
news:1146441731.471931.96960@e56g2000cwe.googlegroups.com...

Hi there,

I've been working on an IDL implementention and I'm having problems
with one of the objects' destructors not being called.

The follow is the structure of my IDL file:

interface IMyBase : IUnknown {
  ....
}

interface IMyDerived : IMyBase {
  ....
}

Now for an implementation, there is no implementation of IMyBase since
I meant it to be used as a base. But we do have...

Class CMyDerived : public IMyDerived {
  public:
     CMyDerived();
     ~CMyDerived()
}

Now to move onto the problem, elsewhere we have a vector containing
pointers:

vector<IMyDerived*> myVector

And now onto the problem, the following will work with the exception
that it doesn not call the destructor!

// stuff things in the vector
for(int i=0; i<10; i++) {
  IMyDerived* pitem = NULL;
  hr = CoCreateInstance(CLSID_CStuff,
     NULL,
     CLSCTX_ALL,
     IID_IMyDerived,
     (void**)&pitem);

     IMyBase* pitem2 = reinterpret_cast<IMyBase*>(pitem);
     myVector.push_back(pitem2);
}

// now we want to delete the stuff.....
// I'm hoping that the destructor in CMyDerived will be called

// attempt 1, this doesn't work
IMyBase* d = myVector[0];
delete d; // no luck
delete [] d; // no luck

// attempt 2, still no luck
IMyBase* d = myVector[0];
IMyDerived* d2 = reinterpret_cast<IMyDerived*>(d);
delete d2; // no luck
delete [] d2; // no luck

// since this stuff is in a COM DLL, I even tried using some of the
IUNKNOWN mechanisms
(myVector[0])->Release(); // no luck
((IMyDerived*) myVector[0])->Release(); // no luck

Nothing I do seems to get my derived class' destructor to go off which
it causing a memory leak over time.

Does anyone know how I can fix this problem?

I was thinking about adding a virtual destructor to the base, but since
the base is only defined via an IDL interface I have no idea how to do
this... or if this would even work... or even on the right track...

Thanks!

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