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IDispatchEx::InvokeEx

Provides access to properties and methods exposed by an IDispatchEx object.

HRESULT InvokeEx(
   DISPID id,
   LCID lcid,
   WORD wFlags,
   DISPARAMS *pdp,
   VARIANT *pVarRes, 
   EXCEPINFO *pei, 
   IServiceProvider *pspCaller 
);

id

Identifies the member. Uses GetDispID or GetNextDispID to obtain the dispatch identifier.

lcid

The locale context in which to interpret arguments. The lcid is passed to InvokeEx to allow the object to interpret its arguments specific to a locale.

wFlags

The legal values for wFlags are:

DISPATCH_PROPERTYGET | DISPATCH_METHOD | DISPATCH_PROPERTYPUT | DISPATCH_PROPERTYPUTREF | DISPATCH_CONSTRUCT

Flags describing the context of the InvokeEx call:

Value

Meaning

DISPATCH_METHOD

The member is invoked as a method. If a property has the same name, both this and the DISPATCH_PROPERTYGET flag may be set (defined by IDispatch).

DISPATCH_PROPERTYGET

The member is retrieved as a property or data member (defined by IDispatch).

DISPATCH_PROPERTYPUT

The member is changed as a property or data member (defined by IDispatch).

DISPATCH_PROPERTYPUTREF

The member is changed by a reference assignment rather than a value assignment. This flag is valid only when the property accepts a reference to an object (defined by IDispatch).

DISPATCH_CONSTRUCT

The member is being used as a constructor. (This is a new value defined by IDispatchEx). The legal values for wFlags are:

DISPATCH_PROPERTYGET DISPATCH_METHOD DISPATCH_PROPERTYPUT DISPATCH_PROPERTYPUTREF DISPATCH_CONSTRUCT

pdp

Pointer to a structure containing an array of arguments, an array of argument DISPIDs for named arguments, and counts for the number of elements in the arrays. See the IDispatch documentation for a full description of the DISPPARAMS structure.

pVarRes

Pointer to the location where the result is to be stored or Null if the caller expects no result. This argument is ignored if DISPATCH_PROPERTYPUT or DISPATCH_PROPERTYPUTREF is specified.

pei

Pointer to a structure that contains exception information. This structure should be filled in if DISP_E_EXCEPTION is returned. Can be Null. See the IDispatch documentation for a full description of the EXCEPINFO structure.

pspCaller

Pointer to a service provider object supplied by the caller, which allows the object to obtain services from the caller. Can be Null.

IDispatchEx::InvokeEx provides all of the same features as IDispatch::Invoke and adds a few extensions:

DISPATCH_CONSTRUCT

Indicates that the item is being used as a constructor.

pspCaller

The pspCaller allows the object access to services provided by the caller. Specific services may be handled by the caller itself or delegated to callers further up the call chain. For example, if a script engine inside a browser makes an InvokeEx call to an external object, the object can follow the pspCaller chain to obtain services from the script engine or browser. (Note that the call chain is not the same as the creation chain—also known as container chain or site chain. The creation chain may be available through some other mechanism such as IObjectWithSite.)

this pointer

When DISPATCH_METHOD is set in wFlags, there may be a "named parameter" for the "this" value. The DISPID will be DISPID_THIS and it must be the first named parameter.

The unused riid parameter in IDispatch::Invoke has been removed.

The puArgArr parameter in IDispatch::Invoke has been removed.

See the IDispatch::Invoke documentation for the following examples:

"Calling a method with no arguments"

"Getting and setting properties"

"Passing parameters"

"Indexed Properties"

"Raising exceptions during Invoke"

"Returning errors"

Returns one of the following values:

S_OK

Success.

DISP_E_BADPARAMCOUNT

The number of elements provided to DISPPARAMS is different from the number of arguments accepted by the method or property.

DISP_E_BADVARTYPE

One of the arguments in rgvarg is not a valid variant type.

DISP_E_EXCEPTION

The application needs to raise an exception. In this case, the structure passed in pei should be filled in.

DISP_E_MEMBERNOTFOUND

The requested member does not exist, or the call to InvokeEx tried to set the value of a read-only property.

DISP_E_NONAMEDARGS

This implementation of IDispatch does not support named arguments.

DISP_E_OVERFLOW

One of the arguments in rgvarg could not be coerced to the specified type.

DISP_E_PARAMNOTFOUND

One of the parameter DISPIDs does not correspond to a parameter on the method.

DISP_E_TYPEMISMATCH

One or more of the arguments could not be coerced.

DISP_E_UNKNOWNLCID

The member being invoked interprets string arguments according to the LCID, and the LCID is not recognized. If the LCID is not needed to interpret arguments, this error should not be returned.

DISP_E_PARAMNOTOPTIONAL

A required parameter was omitted.

VARIANT var;
   BSTR bstrName;
   DISPID dispid;
   IDispatchEx *pdex;
   DISPPARAMS dispparamsNoArgs = {NULL, NULL, 0, 0};

   // Assign to pdex and bstrName
   if (SUCCEEDED(pdex->GetDispID(bstrName, fdexNameCaseSensitive, &dispid)))
   {
      pdex->InvokeEx(dispid, LOCALE_USER_DEFAULT,
         DISPATCH_PROPERTYGET, &dispparamsNoArgs, 
         &var, NULL, NULL);
   }
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