C# 4 and .NET 4

706 ❘ ChaPTer 26 interOp
}
public:
STDMETHOD(Greeting)(BSTR name, BSTR* message);
};
OBJECT_ENTRY_AUTO(__uuidof(COMDemo), CCOMDemo)
code snippet COMServer/COMDemo.h
With this class definition, you have to add the second interface, IMath, as well as the methods that are
defined with the IMath interface:
class ATL_NO_VTABLE CCOMDemo:
public CComObjectRootEx,
public CComCoClass,
public IDispatchImpl
public IDispatchImpl
{
public:
CCOMDemo()
{
}
DECLARE_REGISTRY_RESOURCEID(IDR_COMDEMO)
BEGIN_COM_MAP(CCOMDemo)
COM_INTERFACE_ENTRY(IWelcome)
COM_INTERFACE_ENTRY(IMath)
COM_INTERFACE_ENTRY2(IDispatch, IWelcome)
END_COM_MAP()
DECLARE_PROTECT_FINAL_CONSTRUCT()
HRESULT FinalConstruct()
{
return S_OK;
}
void FinalRelease()
{
}
public:
STDMETHOD(Greeting)(BSTR name, BSTR* message);
STDMETHOD(Add)(long val1, long val2, long* result);
STDMETHOD(Sub)(long val1, long val2, long* result);
};
OBJECT_ENTRY_AUTO(__uuidof(COMDemo), CCOMDemo)
Now, you can implement the three methods in the file COMDemo.cpp with the following code. The CComBSTR
is an ATL class that makes it easier to deal with BSTRs. In the Greeting() method, only a welcome
message is returned, which adds the name passed in the first argument to the message that is returned.
The Add() method just does a simple addition of two values, and the Sub() method does a subtraction and
returns the result:
STDMETHODIMP CCOMDemo::Greeting(BSTR name, BSTR* message)
{
CComBSTR tmp("Welcome, ");
tmp.Append(name);
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