Re: Design of array for holding interface pointer

From:
"Igor Tandetnik" <itandetnik@mvps.org>
Newsgroups:
microsoft.public.vc.atl
Date:
Wed, 18 Apr 2007 10:55:33 -0400
Message-ID:
<OffcemcgHHA.4260@TK2MSFTNGP03.phx.gbl>
aeshiels@gmail.com wrote:

Im writing a COM interface which will hold an array of my IItem3
interface pointers.

     std::vector < CAdapt< CComPtr<IItem3> > > m_aItems;

STDMETHODIMP CMyArray::putItem(IItem3 *pVal)
{

USES_CONVERSION;
CComPtr<IItem3> item3;
               HRESULT hr = pVal->QueryInterface(__uuidof(IItem3),
(void**)&item3);
               if(FAILED(hr))
    return hr;
m_aItems.push_back (item3);

return S_OK;
}


Your code is correct but way overcomplicated. Just do

m_aItems.push_back (pVal);

STDMETHODIMP CMyArray::getItem(IItem3 * * pVal)
{
if (m_aItems.size() == 0)
        return E_FAIL;

CComPtr <IItem3> item3 = ( CComPtr<IItem3> )m_aItems.front ();
               HRESULT hr = item3->QueryInterface(__uuidof(IItem3),
(void**)pVal);
               if(FAILED(hr))
    return hr;


Again, too complicated. Make it

HRESULT hr = m_aItems.front().m_T.CopyTo(pVal);

m_aItems.pop_back();


This looks suspicious. You are returning an element from the front of
the vector, but popping from the back. Is this really what you want?
--
With best wishes,
    Igor Tandetnik

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