IProviderPtr vs. IProvider * : A related problem

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2 total messages Started by Mark Brown Thu, 04 Nov 1999 00:00

#1527

Author: Mark Brown
Date: Thu, 04 Nov 1999 00:00

44 lines
2314 bytes

(Please excuse the cross-post, as I found that this group seems to be
tackling this problem more than the group I previously posted this
too.)

Hi everyone-

After installing patch 1 and 2 for CPP Builder 4, we have encountered
this new phenomenon of type library changes.  I have read the
work-around for getting the exported tables and queries from the app
server to work for the client.  However, another piece of our code
(which I never fully understood) has now broken.

We had a callback implementation in place where the client was passing
a pointer to its sink object to the server so the server could notify
it when needed.  The data type of the object used to be declared as:

    CComPtr <IClientSink> mySinkPointer;

So, I would create my sink by:

    CComObject <TClientSink> *Sink = new CComObject <TClientSink>;
    mySinkPointer = Sink;

Finally, after obtaining a pointer to the server callback object, the
client would pass the pointer to the sink to the server by:

     HRESULT hr = pServerCallbackObject->Connect(mySinkPointer, (long
*)&Cookie);

whereby the Connect method would use the mySinkPointer to pass to the
Advise method of the IConnectionPointImpl.

Whew...now the problem is that originally, the Connect method had a
IClientSink * variable type for the first parameter, and now it has
been changed to IClientSinkPtr variable type.  I can't seem to get the
correct address of my sink sent over to the server callback object due
to this variable type change, and I don't have enough information
about this new variable type.

Anyone have any clues?  Do I need to cast it somehow to a (IClientSink
*) variable on the client and/or server?

Thanks,
Mark Brown

Re: IProviderPtr vs. IProvider * : A related problem

#1381

Author: Mark Brown
Date: Thu, 04 Nov 1999 00:00

32 lines
1565 bytes

Hi-

I found that if I changed the Connect interface method to accept an
IClientSinkPtr * variable instead of a IClientSinkPtr variable, I was
able to successfully get my code to work.

Interesting thing I found...While performing this cast (at the end of
code snip-it):

    CComPtr <IClientSink> mySinkPointer;
    CComObject <TClientSink> *Sink = new CComObject <TClientSink>;
    mySinkPointer = Sink;

   IClientSinkPtr *myClientSinkPtrPtr =
(IClientSinkPtr*)&mySinkPointer;   // <--This cast

an ASSERT error was raised in atlbase.h.  By just ignoring it, the
code worked fine.

Specifically, in lines 325-327:
  // The assert on operator& usually indicates a bug.  If this is
really
  // what is needed, however, take the address of the p member
explicitly.
  T** operator&() { _ASSERTE(p==NULL); return &p; }

Seems like this might be a bug, and should be (p!=NULL).

Comments?

Hope this helps,
Mark

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