Re: Calling COM functions using IDispatch->Invoke(...

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* Alf P. Steinbach:
* Alex:

Alf,
I tried to implement your class,
But it also fails, could you please check out what I’m doing wrong:

SomeCOMObject pComObj; //of course I’ve changed in the constructor
//PROG ID

alfs::DispatchParams dp( 2 );

DISPPARAMS* pDispParam = dp.ptr();

pDispParam->cArgs = 2;
pDispParam->cNamedArgs = 0;

Uh huh. You shouldn't do anything with the innards of the parameters object. But as it happens it looks like the above does nothing, just assigning the values that are already there.

Simply don't do anything.


DISPID dispidNamed = DISPATCH_METHOD;
pDispParam->rgdispidNamedArgs = &dispidNamed;

Oops.

Simply don't do anything.



//or
pDispParam->rgdispidNamedArgs = NULL
//as Sven suggested

This is also bad.

Simply don't do anything.


pDispParam->rgvarg = new VARIANTARG[ 2 ];

pDispParam->rgvarg[ 0 ].vt = VT_ERROR;
pDispParam->rgvarg[ 0 ].lVal = DISP_E_PARAMNOTFOUND;

pDispParam->rgvarg[ 1 ].vt = VT_BSTR;
pDispParam->rgvarg[ 1 ].bstrVal = SysAllocString( L"C:\\Program Files\
\... " );

Ditto, simply don't do anything.

Instead,

dp.setParam( 0, L"Start" );

Sorry, I meant


dp.setParam( 0, L"\C:\\Program Files\..." );

You might need to quote that path since it contains spaces.




pComObj.call( L"Start", dp );


Cheers, & hth.,

- Alf

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