implements (C++)

Article
08/03/2021

Specifies dispatch interfaces that are forced to be members of the IDL coclass.

Syntax

[ implements(
   interfaces={interfaces}, dispinterfaces={dispinterfaces})]

Parameters

interfaces
A comma separated list of the interfaces that will be a member of the IDL coclass. A shorthand method for specifying a single interface is implements( interface_name ).

dispinterfaces
A comma separated list of the dispinterface that will be a member of the IDL coclass. A shorthand method for specifying a single dispinterface is implements(dispinterfaces = dispinterface_name ).

Remarks

By default, only COM-interfaces that are base classes of the coclass are added in the IDL coclass. implements lets you force other interfaces to be IDL coclass members.

Requirements

Attribute context	Value
Applies to	`class`, `struct`
Repeatable	Yes
Required attributes	None
Invalid attributes	None

For more information, see Attribute Contexts.

Examples

The following example is in three parts: an .idl file and its associated .h file, and a C++ file.

Assume the following .idl file, which will be available to the compiler.

// attr_implements.idl
import "docobj.idl";
[ version(1.0), uuid(0ed71801-a1b6-3178-af3b-9431fc00185e) ]
library odod
{
   importlib("stdole2.tlb");
   importlib("olepro32.dll");

   [
      object,    uuid(1AECC9BB-2104-3723-98B8-7CC54722C7DD)
   ]
   interface IBar1 {
      [id(1)] HRESULT bar1();
   };

   [
      dual,    uuid(1AECCABB-2104-3723-98B8-7CC54722C7DD)
   ]
   interface IBar2 {
      [id(1)] HRESULT bar2();
   };

   [
      uuid(1AECC9CC-2104-3723-98B8-7CC54722C7DD)
   ]
   dispinterface ISna {
   properties:

   methods:
      [id(1)] HRESULT sna();
   };

   [
      uuid(159A9BBB-E5F1-33F6-BEF5-6CFAD7A5933F),    version(1.0)
   ]
   coclass CBar {
      interface IBar1;
      interface IBar2;
      dispinterface ISna;
   };
}

And the following .h file, which also needs to be available to the compiler.

// attr_implements.h
// this ALWAYS GENERATED file contains definitions for the interfaces

/* File created by MIDL compiler version 6.00.0361 */
/* at Mon Feb 28 16:30:53 2005 */
/* Compiler settings for attr_implements.idl:
    Oicf, W1, Zp8, env=Win32 (32b run)
    protocol : dce , ms_ext, c_ext, robust
    error checks: allocation ref bounds_check enum stub_data
    VC __declspec() decoration level:
         __declspec(uuid()), __declspec(selectany), __declspec(novtable)
         DECLSPEC_UUID(), MIDL_INTERFACE()
*/
//@@MIDL_FILE_HEADING(  )

#pragma warning( disable: 4049 )  /* more than 64k source lines */

/* verify that the <rpcndr.h> version is high enough to compile this file*/
#ifndef __REQUIRED_RPCNDR_H_VERSION__
#define __REQUIRED_RPCNDR_H_VERSION__ 475
#endif

#include "rpc.h"
#include "rpcndr.h"

#ifndef __RPCNDR_H_VERSION__
#error this stub requires an updated version of <rpcndr.h>
#endif // __RPCNDR_H_VERSION__

#ifndef __attr_implements_h__
#define __attr_implements_h__

#if defined(_MSC_VER) && (_MSC_VER >= 1020)
#pragma once
#endif

/* Forward Declarations */

#ifndef __IBar1_FWD_DEFINED__
#define __IBar1_FWD_DEFINED__
typedef interface IBar1 IBar1;
#endif /* __IBar1_FWD_DEFINED__ */

#ifndef __IBar2_FWD_DEFINED__
#define __IBar2_FWD_DEFINED__
typedef interface IBar2 IBar2;
#endif /* __IBar2_FWD_DEFINED__ */

#ifndef __ISna_FWD_DEFINED__
#define __ISna_FWD_DEFINED__
typedef interface ISna ISna;
#endif /* __ISna_FWD_DEFINED__ */

#ifndef __CBar_FWD_DEFINED__
#define __CBar_FWD_DEFINED__

#ifdef __cplusplus
typedef class CBar CBar;
#else
typedef struct CBar CBar;
#endif /* __cplusplus */

#endif /* __CBar_FWD_DEFINED__ */

/* header files for imported files */
#include "docobj.h"

#ifdef __cplusplus
extern "C"{
#endif

void * __RPC_USER MIDL_user_allocate(size_t);
void __RPC_USER MIDL_user_free( void * );

#ifndef __odod_LIBRARY_DEFINED__
#define __odod_LIBRARY_DEFINED__

/* library odod */
/* [uuid][version] */

EXTERN_C const IID LIBID_odod;

#ifndef __IBar1_INTERFACE_DEFINED__
#define __IBar1_INTERFACE_DEFINED__

/* interface IBar1 */
/* [uuid][object] */

EXTERN_C const IID IID_IBar1;

#if defined(__cplusplus) && !defined(CINTERFACE)

    MIDL_INTERFACE("1AECC9BB-2104-3723-98B8-7CC54722C7DD")
    IBar1
    {
    public:
        BEGIN_INTERFACE
        virtual /* [id] */ HRESULT STDMETHODCALLTYPE bar1( void) = 0;

        END_INTERFACE
    };

#else /* C style interface */

    typedef struct IBar1Vtbl
    {
        BEGIN_INTERFACE

        /* [id] */ HRESULT ( STDMETHODCALLTYPE *bar1 )(         IBar1 * This);

        END_INTERFACE
    } IBar1Vtbl;

    interface IBar1
    {
        CONST_VTBL struct IBar1Vtbl *lpVtbl;
    };

#ifdef COBJMACROS

#define IBar1_bar1(This)\
    (This)->lpVtbl -> bar1(This)

#endif /* COBJMACROS */

#endif /* C style interface */

/* [id] */ HRESULT STDMETHODCALLTYPE IBar1_bar1_Proxy( IBar1 * This);

void __RPC_STUB IBar1_bar1_Stub( IRpcStubBuffer *This,  IRpcChannelBuffer *_pRpcChannelBuffer,  PRPC_MESSAGE _pRpcMessage,  DWORD *_pdwStubPhase);

#endif /* __IBar1_INTERFACE_DEFINED__ */

#ifndef __IBar2_INTERFACE_DEFINED__
#define __IBar2_INTERFACE_DEFINED__

/* interface IBar2 */
/* [auto_handle][uuid][dual] */

EXTERN_C const IID IID_IBar2;

#if defined(__cplusplus) && !defined(CINTERFACE)

    MIDL_INTERFACE("1AECCABB-2104-3723-98B8-7CC54722C7DD")
    IBar2
    {
    public:
        BEGIN_INTERFACE
        virtual /* [id] */ HRESULT STDMETHODCALLTYPE bar2( void) = 0;

        END_INTERFACE
    };

#else /* C style interface */

    typedef struct IBar2Vtbl
    {
        BEGIN_INTERFACE

        /* [id] */ HRESULT ( STDMETHODCALLTYPE *bar2 )(         IBar2 * This);

        END_INTERFACE
    } IBar2Vtbl;

    interface IBar2
    {
        CONST_VTBL struct IBar2Vtbl *lpVtbl;
    };

#ifdef COBJMACROS

#define IBar2_bar2(This)\
    (This)->lpVtbl -> bar2(This)

#endif /* COBJMACROS */

#endif /* C style interface */

/* [id] */ HRESULT STDMETHODCALLTYPE IBar2_bar2_Proxy( IBar2 * This);

void __RPC_STUB IBar2_bar2_Stub( IRpcStubBuffer *This,  IRpcChannelBuffer *_pRpcChannelBuffer,  PRPC_MESSAGE _pRpcMessage,  DWORD *_pdwStubPhase);

#endif /* __IBar2_INTERFACE_DEFINED__ */

#ifndef __ISna_DISPINTERFACE_DEFINED__
#define __ISna_DISPINTERFACE_DEFINED__

/* dispinterface ISna */
/* [uuid] */

EXTERN_C const IID DIID_ISna;

#if defined(__cplusplus) && !defined(CINTERFACE)

    MIDL_INTERFACE("1AECC9CC-2104-3723-98B8-7CC54722C7DD")
    ISna : public IDispatch
    {
    };

#else /* C style interface */

    typedef struct ISnaVtbl
    {
        BEGIN_INTERFACE

        HRESULT ( STDMETHODCALLTYPE *QueryInterface )(         ISna * This,          /* [in] */ REFIID riid,          /* [iid_is][out] */ void **ppvObject);

        ULONG ( STDMETHODCALLTYPE *AddRef )(         ISna * This);

        ULONG ( STDMETHODCALLTYPE *Release )(         ISna * This);

        HRESULT ( STDMETHODCALLTYPE *GetTypeInfoCount )(         ISna * This,          /* [out] */ UINT *pctinfo);

        HRESULT ( STDMETHODCALLTYPE *GetTypeInfo )(         ISna * This,          /* [in] */ UINT iTInfo,          /* [in] */ LCID lcid,          /* [out] */ ITypeInfo **ppTInfo);

        HRESULT ( STDMETHODCALLTYPE *GetIDsOfNames )(         ISna * This,          /* [in] */ REFIID riid,          /* [size_is][in] */ LPOLESTR *rgszNames,          /* [in] */ UINT cNames,          /* [in] */ LCID lcid,          /* [size_is][out] */ DISPID *rgDispId);

        /* [local] */ HRESULT ( STDMETHODCALLTYPE *Invoke )(         ISna * This,          /* [in] */ DISPID dispIdMember,          /* [in] */ REFIID riid,          /* [in] */ LCID lcid,          /* [in] */ WORD wFlags,          /* [out][in] */ DISPPARAMS *pDispParams,          /* [out] */ VARIANT *pVarResult,          /* [out] */ EXCEPINFO *pExcepInfo,          /* [out] */ UINT *puArgErr);

        END_INTERFACE
    } ISnaVtbl;

    interface ISna
    {
        CONST_VTBL struct ISnaVtbl *lpVtbl;
    };

#ifdef COBJMACROS

#define ISna_QueryInterface(This,riid,ppvObject)\
    (This)->lpVtbl -> QueryInterface(This,riid,ppvObject)

#define ISna_AddRef(This)\
    (This)->lpVtbl -> AddRef(This)

#define ISna_Release(This)\
    (This)->lpVtbl -> Release(This)

#define ISna_GetTypeInfoCount(This,pctinfo)\
    (This)->lpVtbl -> GetTypeInfoCount(This,pctinfo)

#define ISna_GetTypeInfo(This,iTInfo,lcid,ppTInfo)\
    (This)->lpVtbl -> GetTypeInfo(This,iTInfo,lcid,ppTInfo)

#define ISna_GetIDsOfNames(This,riid,rgszNames,cNames,lcid,rgDispId)\
    (This)->lpVtbl -> GetIDsOfNames(This,riid,rgszNames,cNames,lcid,rgDispId)

#define ISna_Invoke(This,dispIdMember,riid,lcid,wFlags,pDispParams,pVarResult,pExcepInfo,puArgErr)\
    (This)->lpVtbl -> Invoke(This,dispIdMember,riid,lcid,wFlags,pDispParams,pVarResult,pExcepInfo,puArgErr)

#endif /* COBJMACROS */

#endif /* C style interface */

#endif /* __ISna_DISPINTERFACE_DEFINED__ */

EXTERN_C const CLSID CLSID_CBar;

#ifdef __cplusplus

class DECLSPEC_UUID("159A9BBB-E5F1-33F6-BEF5-6CFAD7A5933F")
CBar;
#endif
#endif /* __odod_LIBRARY_DEFINED__ */

/* Additional Prototypes for ALL interfaces */

/* end of Additional Prototypes */

#ifdef __cplusplus
}
#endif
#endif

In the following program, without implements, IBar1, IBar2, and ISna will not be in the coclass in the generated IDL.

// attr_implements.cpp
// compile with: /LD /link /idlout:out.idl
#define _ATL_ATTRIBUTES 1
#include <atlbase.h>
#include <atlcom.h>
#include "attr_implements.h"   // IDL generated header that contains a definition of the pseudo-interface IBar and pseudo-dispinterface  ISna

[module(name = "MyLib")];

[dispinterface, uuid("00000000-0000-0000-0000-000000000001")]
__interface IMyInterface
{
   [id(0)] long x;
   [id(1)] HRESULT func();
};

[
   coclass, uuid("00000000-0000-0000-0000-000000000002"), implements(interfaces={IBar1,IBar2}, dispinterfaces=ISna)
]
class CMyClass : public IMyInterface, public IBar1,    public IDispatchImpl<IBar2, &__uuidof(IBar2)>, public ISna
{
   long _x;
public:
   long get_x() { return _x; }
   void put_x(long x0) { _x = x0; }
   HRESULT func() { return S_OK; }
   HRESULT __stdcall bar1() { return S_OK; }
   HRESULT __stdcall bar2() { return S_OK; }
   HRESULT __stdcall sna() { return S_OK; }

   virtual HRESULT STDMETHODCALLTYPE ISna::Invoke(         /* [in] */ DISPID dispIdMember,          /* [in] */ REFIID riid,          /* [in] */ LCID lcid,          /* [in] */ WORD wFlags,          /* [out][in] */ DISPPARAMS *pDispParams,          /* [out] */ VARIANT *pVarResult,          /* [out] */ EXCEPINFO *pExcepInfo,          /* [out] */ UINT *puArgErr)
   {
      HRESULT hr = S_OK;
      if (pDispParams == 0) {
         return DISP_E_BADVARTYPE;
      }
      if (pDispParams->cArgs> 0) {
         return DISP_E_BADPARAMCOUNT;
      }
      if (pVarResult != 0) {
         ::VariantInit(pVarResult);
      }
      switch (dispIdMember) {
      case 1:
         {
            if (pDispParams->cArgs != 0) {
               return DISP_E_BADPARAMCOUNT;
            }
            hr = this->sna();
            break;
         }
      default:
         return DISP_E_MEMBERNOTFOUND;
      }
      return hr;
   }
   virtual HRESULT STDMETHODCALLTYPE ISna::GetIDsOfNames(         /* [in] */ REFIID riid,          /* [size_is][in] */ LPOLESTR *rgszNames,          /* [in] */ UINT cNames,          /* [in] */ LCID lcid,          /* [size_is][out] */ DISPID *rgDispId)
   {
      static LPOLESTR names[] = { L"sna" };
      static DISPID dids[] = { 1 };
      for (unsigned int i = 0; i < cNames; ++i) {
         int fFoundIt = 0;
         for (unsigned int j = 0; j < sizeof(names)/sizeof(LPOLESTR); ++j) {
            if (lstrcmpiW(rgszNames[i], names[j]) == 0) {
               fFoundIt = 1;
               rgDispId[i] = dids[j];
               break;
            }
         }
         if (fFoundIt == 0) {
            return DISP_E_UNKNOWNNAME;
         }
      }
      return S_OK;
   }
   virtual HRESULT STDMETHODCALLTYPE ISna::GetTypeInfoCount(unsigned int*  pctinfo)
   {
      if (pctinfo == NULL) {
         return E_POINTER;
      }
      CComPtr<ITypeInfo> spTypeInfo;
      *pctinfo =
                  (SUCCEEDED(TypeInfoHelper(__uuidof(ISna), 0, &spTypeInfo))) ? 1 : 0;
      return S_OK;
   }
   virtual HRESULT STDMETHODCALLTYPE ISna::GetTypeInfo(unsigned int iTInfo, LCID lcid, ITypeInfo** ppTInfo)
   {
      if (iTInfo != 0) {
         return DISP_E_BADINDEX;
      }
      return TypeInfoHelper(__uuidof(ISna), lcid, ppTInfo);
   }
   BEGIN_COM_MAP(CMyClass)
      COM_INTERFACE_ENTRY(IBar1)
      COM_INTERFACE_ENTRY(IBar2)
      COM_INTERFACE_ENTRY(ISna)
   END_COM_MAP()
};

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implements (C++)

Syntax

Parameters

Remarks

Requirements

Examples

See also

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