CComQIPtr and XML question
in [MFC]
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From: dushkin on 25 May 2010 09:31 Hi all! On VC6 this code worked perfectly: MSXML::IXMLDOMDocumentPtr CXMLDocItem::GetXMLNode() { CComQIPtr<MSXML::IXMLDOMDocument> docPtr = CXMLItem::GetXMLNode(); return docPtr; } It is a part of Expat XML wrapping library. But, on VS2008 it gives me the following error: error C2664: '_com_ptr_t<_IIID>::_com_ptr_t(int)' : cannot convert parameter 1 from 'ATL::CComQIPtr<T>' to 'int' 1> with 1> [ 1> _IIID=_com_IIID<MSXML::IXMLDOMDocument,& _GUID_2933bf81_7b36_11d2_b20e_00c04f983e60> 1> ] 1> and 1> [ 1> T=MSXML::IXMLDOMDocument 1> ] 1> No user-defined-conversion operator available that can perform this conversion, or the operator cannot be called
From: Giovanni Dicanio on 26 May 2010 05:59 "dushkin" <taltene(a)gmail.com> wrote: > On VC6 this code worked perfectly: > > MSXML::IXMLDOMDocumentPtr CXMLDocItem::GetXMLNode() > { > CComQIPtr<MSXML::IXMLDOMDocument> docPtr = CXMLItem::GetXMLNode(); > return docPtr; > } > > It is a part of Expat XML wrapping library. > > But, on VS2008 it gives me the following error: > > error C2664: '_com_ptr_t<_IIID>::_com_ptr_t(int)' : cannot convert > parameter 1 from 'ATL::CComQIPtr<T>' to 'int' The _com_ptr_t constructor overload with 'int' parameter is just provided to allow the NULL assignment (issuing an error if a non-NULL value is passed). So, it seems to me that the VC compiler is choosing a wrong overload for _com_ptr_t constructor. I think the correct overload should be the one taking a COM interface pointer (MSXML::IXMLDOMDocument *). Have you tried like this? return docPtr.Detach(); HTH, Giovanni
From: Giovanni Dicanio on 26 May 2010 06:22 "Giovanni Dicanio" <giovanniDOTdicanio(a)REMOVEMEgmail.com> wrote: >> On VC6 this code worked perfectly: >> >> MSXML::IXMLDOMDocumentPtr CXMLDocItem::GetXMLNode() >> { >> CComQIPtr<MSXML::IXMLDOMDocument> docPtr = CXMLItem::GetXMLNode(); >> return docPtr; >> } >> >> [...] >> >> error C2664: '_com_ptr_t<_IIID>::_com_ptr_t(int)' : cannot convert >> parameter 1 from 'ATL::CComQIPtr<T>' to 'int' > > The _com_ptr_t constructor overload with 'int' parameter is just provided > to allow the NULL assignment (issuing an error if a non-NULL value is > passed). > So, it seems to me that the VC compiler is choosing a wrong overload for > _com_ptr_t constructor. BTW: I'm curious... is it necessary to pass to CComQIPtr? Would it be possible to just return the result of CXMLItem::GetXMLNode? Giovanni
From: dushkin on 27 May 2010 03:20 On May 26, 12:59 pm, "Giovanni Dicanio" <giovanniDOTdica...(a)REMOVEMEgmail.com> wrote: > "dushkin" <talt...(a)gmail.com> wrote: > > On VC6 this code worked perfectly: > > > MSXML::IXMLDOMDocumentPtr CXMLDocItem::GetXMLNode() > > { > > CComQIPtr<MSXML::IXMLDOMDocument> docPtr = CXMLItem::GetXMLNode(); > > return docPtr; > > } > > > It is a part of Expat XML wrapping library. > > > But, on VS2008 it gives me the following error: > > > error C2664: '_com_ptr_t<_IIID>::_com_ptr_t(int)' : cannot convert > > parameter 1 from 'ATL::CComQIPtr<T>' to 'int' > > The _com_ptr_t constructor overload with 'int' parameter is just provided to > allow the NULL assignment (issuing an error if a non-NULL value is passed). > So, it seems to me that the VC compiler is choosing a wrong overload for > _com_ptr_t constructor. > > I think the correct overload should be the one taking a COM interface > pointer (MSXML::IXMLDOMDocument *). > Have you tried like this? > > return docPtr.Detach(); > > HTH, > Giovanni thank you Giovanni. return docPtr.Detach() resulted with: c:\program files\microsoft visual studio 9.0\vc\include\comip.h(852) : error C2227: left of '->QueryInterface' must point to class/struct/ union/generic type 1> type is 'MSXML::IXMLDOMElement **' 1> c:\program files\microsoft visual studio 9.0\vc\include \comip.h(243) : see reference to function template instantiation 'HRESULT _com_ptr_t<_IIID>::_QueryInterface<_InterfaceType*>(_InterfacePtr) throw()' being compiled 1> with 1> [ 1> _IIID=_com_IIID<MSXML::IXMLDOMElement,& _GUID_2933bf86_7b36_11d2_b20e_00c04f983e60>, 1> _InterfaceType=MSXML::IXMLDOMElement *, 1> _InterfacePtr=MSXML::IXMLDOMElement ** 1> ] 1> d:\cm_projects\spark manager\spark manager\xml \xmlwrapper.cpp(647) : see reference to function template instantiation '_com_ptr_t<_IIID> &_com_ptr_t<_IIID>::operator =<T*>(_InterfaceType *)' being compiled 1> with 1> [ 1> _IIID=_com_IIID<MSXML::IXMLDOMElement,& _GUID_2933bf86_7b36_11d2_b20e_00c04f983e60>, 1> T=MSXML::IXMLDOMElement, 1> _InterfaceType=MSXML::IXMLDOMElement * 1> ] The issue here is that these are not classes that I wrote, but I got them from another project, so I am not into large modifications here. I hope the changes are minor, because the only change which caused the problem is changing the environment and not the code.
From: dushkin on 27 May 2010 03:36
On May 26, 12:59 pm, "Giovanni Dicanio" <giovanniDOTdica...(a)REMOVEMEgmail.com> wrote: > "dushkin" <talt...(a)gmail.com> wrote: > > On VC6 this code worked perfectly: > > > MSXML::IXMLDOMDocumentPtr CXMLDocItem::GetXMLNode() > > { > > CComQIPtr<MSXML::IXMLDOMDocument> docPtr = CXMLItem::GetXMLNode(); > > return docPtr; > > } > > > It is a part of Expat XML wrapping library. > > > But, on VS2008 it gives me the following error: > > > error C2664: '_com_ptr_t<_IIID>::_com_ptr_t(int)' : cannot convert > > parameter 1 from 'ATL::CComQIPtr<T>' to 'int' > > The _com_ptr_t constructor overload with 'int' parameter is just provided to > allow the NULL assignment (issuing an error if a non-NULL value is passed). > So, it seems to me that the VC compiler is choosing a wrong overload for > _com_ptr_t constructor. > > I think the correct overload should be the one taking a COM interface > pointer (MSXML::IXMLDOMDocument *). > Have you tried like this? > > return docPtr.Detach(); > > HTH, > Giovanni Giovanni, I manged to compile like this: MSXML::IXMLDOMDocumentPtr temp; temp.Attach(docPtr.Detach()); return temp; Thanks! |