Is COM interface support method override?

COM does not support method overloading.
In your case you could make the first parameter a VARIANT so you can investigate the type of the param at runtime. In your C++ implementation you might then use method overloading, e.g.:

interface ITest : IDispatch
{
HRESULT AddParameter([in] VARIANT Param);
};

class YourTestImpl : ITest
{
void addParam(bool);
void addParam(float);

HRESULT AddParameter(VARIANT Param)
{
switch(Param.vt)
{
case VT_BOOL:
addParam(Param.boolVal != VARIANT_FALSE);
break;

case VT_R4: // float
addParam(Param.fltVal);
break;

default:
return E_INVALIDARG;
}

return S_OK;
}
};

HTH,
SvenC

SvenC at 2007-9-9 >

I am just guessing here: COM should be useable from different languages and not all of them support overloding. Most important VB <= version 6, which I would name the most prominent language with COM support.

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SvenC

SvenC at 2007-9-9 >