CreateDispTypeInfo function (oleauto.h)

Article
04/02/2021

Creates simplified type information for use in an implementation of IDispatch.

Syntax

HRESULT CreateDispTypeInfo(
  INTERFACEDATA *pidata,
  LCID          lcid,
  ITypeInfo     **pptinfo
);

Parameters

pidata

The interface description that this type information describes.

lcid

The locale identifier for the names used in the type information.

pptinfo

On return, pointer to a type information implementation for use in DispGetIDsOfNames and DispInvoke.

Return value

This function can return one of these values.

Return code	Description
S_OK	The interface is supported.
E_INVALIDARG	Either the interface description or the LCID is not valid.
E_OUTOFMEMORY	Insufficient memory to complete the operation.

Remarks

You can construct type information at run time by using CreateDispTypeInfo and an INTERFACEDATA structure that describes the object being exposed.

The type information returned by this function is primarily designed to automate the implementation of IDispatch. CreateDispTypeInfo does not return all of the type information described in Type Description Interfaces. The argument pidata is not a complete description of an interface. It does not include Help information, comments, optional parameters, and other type information that is useful in different contexts.

Accordingly, the recommended method for providing type information about an object is to describe the object using the Object Description Language (ODL), and to compile the object description into a type library using the Microsoft Interface Definition Language (MIDL) compiler.

To use type information from a type library, use the LoadTypeLib and GetTypeInfoOfGuid functions instead of CreateDispTypeInfo. For more information Type Description Interfaces.

Examples

The code that follows creates type information from INTERFACEDATA to expose the CCalc object.

static METHODDATA NEARDATA rgmdataCCalc[] =
{
      PROPERTY(VALUE,  IMETH_ACCUM,    IDMEMBER_ACCUM,    VT_I4),
      PROPERTY(ACCUM,  IMETH_ACCUM,    IDMEMBER_ACCUM,    VT_I4),
      PROPERTY(OPND,   IMETH_OPERAND,  IDMEMBER_OPERAND,  VT_I4),
      PROPERTY(OP,     IMETH_OPERATOR, IDMEMBER_OPERATOR, VT_I2),
      METHOD0(EVAL,    IMETH_EVAL,     IDMEMBER_EVAL,     VT_BOOL),
      METHOD0(CLEAR,   IMETH_CLEAR,    IDMEMBER_CLEAR,    VT_EMPTY),
      METHOD0(DISPLAY, IMETH_DISPLAY,  IDMEMBER_DISPLAY,  VT_EMPTY),
      METHOD0(QUIT,    IMETH_QUIT,     IDMEMBER_QUIT,     VT_EMPTY),
      METHOD1(BUTTON,  IMETH_BUTTON,   IDMEMBER_BUTTON,   VT_BOOL),
};

INTERFACEDATA NEARDATA g_idataCCalc =
{
   rgmdataCCalc, DIM(rgmdataCCalc)
};

// Use Dispatch interface API functions to implement IDispatch.
CCalc *
CCalc::Create()
{
   HRESULT hresult;
   CCalc * pcalc;
   CArith * parith;
   ITypeInfo * ptinfo;
   IUnknown * punkStdDisp;
   extern INTERFACEDATA NEARDATA g_idataCCalc;

   if((pcalc = new CCalc()) == NULL)
      return NULL;
   pcalc->AddRef();

   parith = &(pcalc->m_arith);

   // Build type information for the functionality on this object that
   // is being exposed for external programmability.
   hresult = CreateDispTypeInfo(
      &g_idataCCalc, LOCALE_SYSTEM_DEFAULT, &ptinfo);
   if(hresult != NOERROR)
      goto LError0;

   // Create an aggregate with an instance of the default
   // implementation of IDispatch that is initialized with 
   // type information.
   hresult = CreateStdDispatch(
      pcalc,            // Controlling unknown.
      parith,            // Instance to dispatch on.
      ptinfo,            // Type information describing the instance.
      &punkStdDisp);

   ptinfo->Release();

   if(hresult != NOERROR)
      goto LError0;

   pcalc->m_punkStdDisp = punkStdDisp;

   return pcalc;

LError0:;
   pcalc->Release();
   return NULL;
}

Requirements

Requirement	Value
Target Platform	Windows
Header	oleauto.h
Library	OleAut32.lib
DLL	OleAut32.dll

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