com_interface_entry (C++)

Articolo
01/03/2018

The latest version of this topic can be found at com_interface_entry (C++).

Adds an interface entry into the COM map of the target class.

Syntax

  
     [ com_interface_entry(   
  com_interface_entry  
) ]

Parameters

com_interface_entry
A string containing the actual text of the entry. For a list of possible values, see COM_INTERFACE_ENTRY Macros.

Remarks

The com_interface_entry C++ attribute inserts the unabridged contents of a character string into the COM interface map of the target object. If the attribute is applied once to the target object, the entry is inserted into the beginning of the existing interface map. If the attribute is applied repeatedly to the same target object, the entries are inserted at the beginning of the interface map in the order they are received.

This attribute requires that the coclass, progid, or vi_progid attribute (or another attribute that implies one of these) also be applied to the same element. If any single attribute is used, the other two are automatically applied. For example, if progid is applied, vi_progid and coclass are also applied.

Because the first usage of com_interface_entry causes the new interface to be inserted at the beginning of the interface map, it must be one of the following COM_INTERFACE_ENTRY types:

COM_INTERFACE_ENTRY
COM_INTERFACE_ENTRY_IID
COM_INTERFACE_ENTRY2
COM_INTERFACE_ENTRY2_IID

Additional usages of the com_interface_entry attribute can use all supported COM_INTERFACE_ENTRY types.

This restriction is necessary because ATL uses the first entry in the interface map as the identity IUnknown; therefore, the entry must be a valid interface. For example, the following code sample is invalid because the first entry in the interface map does not specify an actual COM interface.

[ coclass, com_interface_entry =  
    "COM_INTERFACE_ENTRY_NOINTERFACE(IDebugTest)"  
]  
   class CMyClass  
   {  
   };

Example

The following code adds two entries to the existing COM interface map of CMyBaseClass. The first is a standard interface, and the second hides the IDebugTest interface.

// cpp_attr_ref_com_interface_entry.cpp  
// compile with: /LD  
#define _ATL_ATTRIBUTES  
#include "atlbase.h"  
#include "atlcom.h"  
  
[module (name ="ldld")];  
  
[ object,  
  uuid("7dbebed3-d636-4917-af62-c767a720a5b9")]  
__interface IDebugTest{};  
  
[ object,  
  uuid("2875ceac-f94b-4087-8e13-d13dc167fcfc")]  
__interface IMyClass{};  
  
[ coclass,  
  com_interface_entry ("COM_INTERFACE_ENTRY (IMyClass)"),  
  com_interface_entry ("COM_INTERFACE_ENTRY_NOINTERFACE(IDebugTest)"),  
  uuid("b85f8626-e76e-4775-b6a0-4826a9e94af2")  
]  
  
class CMyClass: public IMyClass, public IDebugTest  
{  
};

The resulting COM object map for CMyBaseClass is as follows:

BEGIN_COM_MAP
(CMyClass)  
    COM_INTERFACE_ENTRY (IMyClass)  
    COM_INTERFACE_ENTRY_NOINTERFACE
(IDebugTest)  
    COM_INTERFACE_ENTRY
(IMyClass)  
    COM_INTERFACE_ENTRY2
(IDispatch, IMyClass)  
    COM_INTERFACE_ENTRY
(IDebugTest)  
    COM_INTERFACE_ENTRY
(IProvideClassInfo)  
END_COM_MAP
()

Requirements

Attribute Context

Applies to	class, `struct`
Repeatable	Yes
Required attributes	One or more of the following: coclass, progid, or vi_progid.
Invalid attributes	None

For more information about the attribute contexts, see Attribute Contexts.

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