event_receiver attribute

Creates an event receiver (sink).

Note

Event attributes in native C++ are incompatible with Standard C++. They don't compile when you specify /permissive- conformance mode.

Syntax

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

Parameters

type
An enumeration of one of the following values:

• native for unmanaged C/C++ code (default for native classes).

• com for COM code. This value requires that you include these header files:

  #define _ATL_ATTRIBUTES
  #include <atlbase.h>
  #include <atlcom.h>
  

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 the ones they're hooked to in the event source. The event receiver handler names must match the names specified in the relevant event source interface. Use coclass when layout_dependent is true. It's slightly more efficient to specify true.

• false (default) means that the calling convention and storage class (virtual, static, and others) don't have to match the event method and the handlers. The handler names also don't need to match the event source interface method names.

Remarks

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

event_receiver is used 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 disassociate them.

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

Note

A templated class or struct cannot contain events.

Requirements

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

For more information, see Attribute contexts.

See also

Compiler attributes
event_source
__event
__hook
__unhook
Class attributes