Re: Sharing a smart pointer between threads

"Igor Tandetnik" <>
Mon, 21 Aug 2006 13:25:58 -0400
PaulH <> wrote:

I have a COM object smart pointer I'd like to share between threads
(as in the code below). The object works great in the thread it was
created in, but I get an exception when I use it in the thread I'm
sending it to.

In general, you can't do that. The interface pointer has to be
marshalled before it can be used in a different apartment. The easiest
way to do this in ATL is probably with CComGITPtr:

MyLib::IInterfacePtr m_Obj;
    CComGITPtr<MyLib::IInterface> gitPtr(m_Obj);
    DWORD cookie = gitPtr.Detach();
    m_dialog->PostMessage(MYWM_UPDATE, cookie);

CMyDlg::OnUpdateMsg(WPARAM wParam, LPARAM /*lParam*/)
    DWORD cookie = static_cast<DWORD>(wParam);
    CComGITPtr<MyLib::IInterface> gitPtr(cookie);

    MyLib::IInterfacePtr pObj;


With best wishes,
    Igor Tandetnik

With sufficient thrust, pigs fly just fine. However, this is not
necessarily a good idea. It is hard to be sure where they are going to
land, and it could be dangerous sitting under them as they fly
overhead. -- RFC 1925

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