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In a my c++ dll do like this:

my dll headerfile(eg:test.h):

(1) define a callback interface class:

class CClassCallback
   virtual HRESULT OnAdded() = 0;
   virtual HRESULT OnDeled() = 0;
   virtual HRESULT OnFailed() = 0;

(2) a struct like this:
struct SAType
  CString         strTest;
  int             nTest;
  CClassCallback* pClassCallback;

(3)a object interface class like:
class CTestInterface
	virtual HRESULT Test1(SAType* pTest) = 0;
	virtual HRESULT Test2() = 0;
	virtual void Release() = 0;

(4) the only export dll function:
__declspec(dllexport) CTestInterface* ConstructInterface();

my dll cppfile(eg:test.cpp):

(1) derived a class from CTestInterface
class CTestObject:public CTestInterface
	HRESULT Test1(SAtype& Test) 
		m_sType = Test;
	HRESULT Test2()
	void Release()
		delete this; //delete this object
	void InnerDemoFuc()
//in some condition callback the app by a callback object
	SAtype m_sType;

(2) construct a object and return its interface:
CTestInterface* ConstructInterface()
    return new CTestObject();

that's ok for dll.(real code is more complex)

when I use my dll in MFC UI APP like this:
(1) derive a class from CClassCallback:
class CClassCallbackEx : public CClassCallback
	virtual HRESULT OnAdded()
		.....//do UI app job independly from dll..
	virtual HRESULT OnDeled()
	virtual HRESULT OnFailed()

// can add other func ,var for app needs.

(2) Use the dll like this:
//construct a dll's object,and get its interface
        CTestInterface* m_pInterface = ConstructInterface(); 
 	SAType sAtype;
//new a callback object 
	sAtype->pClassCallback = new CClassCallbackEx();

// all are ok ,delete the ojbject through interface
       delete (CClassCallbackEx)sAtype->pClassCallback ;

run ok.
but when i want use my dll in c# + .net UI app,some questions:
(1) i cannot get the CTestObject instance's interface's member function,
because the interface class is not export.i try to get the object's virture function table,failed.
(2) i have to derive a class from c++ interface in c# code, and use in C++dll, means ojbect callback, not funccallback (OOP)
i donot know how to do.

other words:
(1) C# use a C++Dll ojbect through virture class
(2) C++dll use a C# object through virture class

Give me some suggestions,pls
Updated 30-Jun-10 4:44am
Richard MacCutchan 30-Jun-10 7:57am    
There is no word 'virture', try 'virtual' and it may compile.
liuyunhong 30-Jun-10 9:42am    
You are right, mis spell, just in nodepad

1 solution

I would suggest usage of managed C++ as a "wrapper" around the native C++ library. Later you can consume it in your C# (VB) code as you want.
Share this answer
liuyunhong 1-Jul-10 3:33am    
Your suggestion is one direction.
I want to wrapper a COM dll,the the C# app interop the COM DLL, May be it is a better solution.
voloda2 1-Jul-10 3:53am    
If your DLL is COM than it's better to use COM interop. Otherwise I would prefer the managed C++, which will allow you to have event delegates etc.
liuyunhong 2-Jul-10 3:31am    
yes, managed C++ wrapper will ok. but i donot like managed C++.
if i work for unmanaged C++ is the best, or C# is the best.

And I am trying to build a ATL COM DLL for the raw dll. use the Event in C# to get the Objiect callback function.

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