IDispatch Invoke()返回类型不匹配 [英] IDispatch Invoke() returns Type mismatch
问题描述
我无法成功调用 create_session
成员.返回类型不匹配
I'm unable to successfully invoke create_session
member. It's return Type mismatch
// COM class -> member
virtual HRESULT __stdcall create_session(
/*[in]*/ BSTR pbszName,
/*[in]*/ long i32Value ) = 0;
尝试如下调用 create_session
方法:
// test.cpp
HRESULT create_session( IDispatch *dispatch, WCHAR *member ) {
// WCHAR *member = tlib_help::s2ws( "create_session" );
DISPID dispid = -1;
HRESULT hr = dispatch->GetIDsOfNames( IID_NULL, &member, 1, LOCALE_SYSTEM_DEFAULT, &dispid );
if ( SUCCEEDED( hr ) ) {
DISPPARAMS *dispparams = new DISPPARAMS( );
dispparams->cArgs = 2;
dispparams->cNamedArgs = 1;
VARIANTARG *rgvarg = new VARIANTARG[dispparams->cArgs];
rgvarg[0].vt = VARENUM::VT_BSTR;
rgvarg[0].bstrVal = _bstr_t( "loing_info" );
rgvarg[1].vt = VARENUM::VT_UI4;
rgvarg[1].lVal = 12;//i32Value;
dispparams->rgvarg = rgvarg;
dispparams->rgdispidNamedArgs = &dispid;
EXCEPINFO pExcepInfo; UINT puArgErr;
HRESULT hr;
VARIANT pVarResult;
hr = dispatch->Invoke(
dispid, IID_NULL, LOCALE_SYSTEM_DEFAULT, DISPATCH_METHOD,
dispparams, &pVarResult, &pExcepInfo, &puArgErr
);
delete dispparams;
delete[] rgvarg;
}
return hr;
}
我无法弄清楚,此错误的原因是什么.
I'm unable to figure it out, what is the reason of this error.
推荐答案
The IDispatch::Invoke()
method must be called with parameters in reverse order, as stated in the official documentation:
参数在数组rgvarg []中传递,其编号为在cArgs中传递的参数.数组中的参数应放在从最后到第一个,因此rgvarg [0]具有最后一个参数,并且rgvarg [cArgs -1]具有第一个参数.
The arguments are passed in the array rgvarg[ ], with the number of arguments passed in cArgs. The arguments in the array should be placed from last to first, so rgvarg[0] has the last argument and rgvarg[cArgs -1] has the first argument.
此外,在您的情况下,您不需要命名参数",仅需要位置参数".如果 cNamedArgs
为0,则 rgvarg []
的所有元素都代表位置参数.
Also, in your case, you don't need "named arguments", only "positional arguments". If cNamedArgs
is 0, all of the elements of rgvarg[ ]
represent positional arguments.
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