asked on

DLL COM Object Instantiation

I have a COM Object IUserList that lives in a DLL and is a pure ATL COM object (free threaded, supports ierrorinfo, dual interface). When I go to use it in another program as a smart pointer IUserList or try using it with CComObject< I get a huge number of errors like the following

E:\iwire\UsersBO\Users.cpp(64) : error C2259: 'IUserList' : cannot instantiate abstract class due to following members:
e:\iwire\usersbo\debug\userobjects.tlh(107) : see declaration of 'IUserList'
E:\iwire\UsersBO\Users.cpp(64) : warning C4259: 'long __stdcall IUnknown::QueryInterface(const struct _GUID &,void ** )' : pure virtual function was not defined
c:\program files\microsoft visual studio\vc98\include\unknwn.h(109) : see declaration of 'QueryInterface'
E:\iwire\UsersBO\Users.cpp(64) : warning C4259: 'unsigned long __stdcall IUnknown::AddRef(void)' : pure virtual function was not defined
c:\program files\microsoft visual studio\vc98\include\unknwn.h(113) : see declaration of 'AddRef'
E:\iwire\UsersBO\Users.cpp(64) : warning C4259: 'unsigned long __stdcall IUnknown::Release(void)' : pure virtual function was not defined
c:\program files\microsoft visual studio\vc98\include\unknwn.h(115) : see declaration of 'Release'
E:\iwire\UsersBO\Users.cpp(64) : warning C4259: 'long __stdcall IDispatch::GetTypeInfoCount(unsigned int *)' : pure virtual function was not defined
c:\program files\microsoft visual studio\vc98\include\oaidl.h(2697) : see declaration of 'GetTypeInfoCount'
E:\iwire\UsersBO\Users.cpp(64) : warning C4259: 'long __stdcall IDispatch::GetTypeInfo(unsigned int,unsigned long,struct ITypeInfo ** )' : pure virtual function was not defined
c:\program files\microsoft visual studio\vc98\include\oaidl.h(2700) : see declaration of 'GetTypeInfo'
E:\iwire\UsersBO\Users.cpp(64) : warning C4259: 'long __stdcall IDispatch::GetIDsOfNames(const struct _GUID &,unsigned short ** ,unsigned int,unsigned long,long *)' : pure virtual function was not defined
c:\program files\microsoft visual studio\vc98\include\oaidl.h(2705) : see declaration of 'GetIDsOfNames'
E:\iwire\UsersBO\Users.cpp(64) : warning C4259: 'long __stdcall IDispatch::Invoke(long,const struct _GUID &,unsigned long,unsigned short,struct tagDISPPARAMS *,struct tagVARIANT *,struct tagEXCEPINFO *,unsigned int *)' : pure virtual function was no
t defined

those are a few (there are more). What is going on here and how do I instance my object?

thinh

Hi SD_Adept,
How do you declare smart pointer IUserList. Could you post some code.

Thinh.

thinh

Hi SD_Adept,
How do you declare smart pointer IUserList. Could you post some code.

Thinh.

ShaunWilde

an easy way is to use the #import method

example

#import "yourdll.dll" no_namespaces named_guids

the above statement generates 2 files (.tli,.tlh) that can be found in the output directory for that build

then you can use the smart pointers that are generated within

IUserListPtr ptrUserList;

ptrUserList.Create(CLSID_???);

SD_Adept

ASKER

I am indeed using the import statement. And for whatever reason, it doesn't create the right stuff, or the stuff it does create, requires something else of which I am not aware......

SD_Adept

ASKER

I am trying to use it by doing

IUserList m_iUserList;

also, i tried

CComObject<IUserList> m_iUserList;

although, I will say that IUserList *m_piUserList; does work, but that doesn't give me the object!!!

ShaunWilde

what does your #import statement look like ?

ShaunWilde

> ptrUserList.Create(CLSID_???);

should be CreateInstance :)

> I will say that IUserList *m_piUserList; does work

you will have to create an instance of it

mandhjo

If you want to use a smart pointer, you should declare your variable as...

IUserListPtr m_iUserList

(note the "Ptr")

mandhjo

Are you specifically including any headers? This could be your problem. The #import will give all the declarations that you need. If you were also including a header file that declared your object, you could be having problems.

SD_Adept

ASKER

it seems that I can run CreateInstance (api) and get it to work. But I am fully unable to use the smart pointers, which is what this is all about in the first place. :/

GlennDean

Are you using CComObject in an AppWizard generated program? If so, then you have to add full ATL support for your program. To do this, you need to do 3 things:
1. In stdafx.h, add
#include <atlbase.h>
extern CComModule _Module;
#include <atlcom.h>
2. In stdafx.cpp, add #include <atlimpl.cpp>
3. In your app's .cpp file, add
CComModule _Module
as a global variable. Then in your InitInstance function, add
_Module.Init(NULL,NULL);
AfxOleInit();

Glenn

ShaunWilde

or you can use the C++ template version _com_ptr_t without requiring com support which is what #import uses and is defined in <comdef.h>

again I ask what does you #import statement look like as your problem may be as simple as not using the correct namespace

SD_Adept

ASKER

its not a matter of not having COM support. Its a matter of not being able to instance a COM object I've created in a DLL within a COM/ATL system service. It keeps giving me errors (which pasted at the very beginning of this question).

mandhjo

How are you declaring your smart pointer? In your comment on 4/18 you said that you are declaring your pointer as...

>>IUserList m_iUserList;
>>also, i tried
>>CComObject<IUserList> m_iUserList;

To use it as a smart pointer, you should declare it as I mentioned above...

IUserListPtr m_iUserList;

Note the *Ptr* at the end of IUserList. Are you doing this?

SD_Adept

ASKER

like I said earlier. I can do that. But that only gives me a pointer that I can't use because the interface hasn't been instanced yet. Or am I missing something?

ASKER CERTIFIED SOLUTION

mandhjo

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ShaunWilde

> HRESULT hrReturn = m_iUserList.CreateInstance(CLSID_UserList); // the CLSID will be declared in the .tlh file generated by the import.

I mentioned this earlier :)