Returning S_FALSE from a C# COM dll
- by AntonyW
I have a method defined in IDL as follows :
interface IMyFunc : IDispatch
{
[id(1), helpstring("method GetNextFunction")] HRESULT GetNextFunction([in,out] long* lPos, [out, retval] BSTR* bstrName);
}
Using C++ I always implemented this as follows :
STDMETHODIMP CMyFunc::GetNextFunction(long *nID, long *lPos, BSTR *bstrName)
{
if ( function to return )
{
// setup return values;
return S_OK;
}
else
{
// just exit
return S_FALSE;
}
}
Now I am implementing this in C# and have used tlbimp on the type library and ended up with :
public string GetNextFunction(ref int nID, ref int lPos)
I understand that this is because [out, retval] is used as the return type instead of the HRESULT as in C++. Is there a simple way to return the S_OK / S_FALSE values without changing the method definition? The only way I can see is that I have to use ildasm / ilasm to add preservesig so I end up with something like this :
public int GetNextFunction(ref int nID, ref int lPos, ref string bstrName)
I was wondering if there was some other way without doing the il compilation step.
