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event_receiver

Creates an event receiver (sink).

[ event_receiver(
   type 
   [, layout_dependent=false] 
) ]

Parameters

type
An enumeration of one of the following values:
  • native for unmanaged C/C++ code (default for unmanaged classes).
  • com for COM code. This value requires that you include the following header files:
       #define _ATL_ATTRIBUTES
       #include <atlbase.h>
       #include <atlcom.h>
    
  • managed for Managed Extensions for C++ code (default for managed classes).
layout_dependent
Specify layout_dependent only if type=com. layout_dependent is a Boolean:
  • true means that the signature of the delegates in the event receiver must exactly match those to which they are hooked in the event source. The event receiver handler names must match the names specified in the relevant event source interface. You must use coclass when layout_dependent is true. It is slightly more efficient to specify true.
  • false (default) means that the calling convention and storage class (virtual, static, and others) do not have to match the event method and the handlers; nor do the handler names need to match the event source interface method names.

Attribute Context

Applies to class, struct
Repeatable No
Required attributes coclass when layout_dependent=true
Invalid attributes None

For more information, see Attribute Contexts.

Remarks

The event_receiver C++ attribute specifies that the class or structure to which it is applied will be an event receiver, using the Visual C++ unified event model.

event_receiver is used in conjunction with the event_source attribute and the __hook and __unhook keywords. Use event_source to create event sources. Use __hook within an event receiver's methods to associate ("hook") event receiver methods to the events of an event source. Use __unhook to dissociate them.

The default for type is native unless the class is managed, in which case the default is managed.

layout_dependent is only specified for COM event receivers (type=com). The default for layout_dependent is false.

Note   (For programmers targeting the .NET Framework) If you want to use existing COM or unmanaged C++ event source objects with your managed event receiver objects, you can access their events by using pointers to those COM or unmanaged C++ source objects in your managed event receiver class.

Example

The topic Event Handling in Visual C++ contains code examples using event handling attributes and keywords.

See Also

Compiler Attributes | event_source | __event | __hook | __unhook | Class Attributes | Attributes Samples

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