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event_source attribute

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Creates an event source.

Note

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

Syntax

[ event_source(type, optimize=[speed | size], decorate=[true | 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. Use coclass when type=com. This value requires that you include the following header files:

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

optimize
When type is native, you can specify optimize=size, to indicate that there are 4 bytes of storage (minimum) for all events in a class or optimize=speed (the default) to indicate that there are 4 * (# of events) bytes of storage.

decorate
When type is native, you can specify decorate=false, to indicate that the expanded name in the merged (.mrg) file shouldn't include the enclosing class name. /Fx lets you generate .mrg files. decorate=false, which is the default, results in fully qualified type names in the merged file.

Remarks

The event_source C++ attribute specifies that the class or structure to which it's applied will be an event source.

event_source is used in conjunction with the event_receiver attribute and the __event keyword. Use event_receiver to create event receivers. Use __event on methods within the event source to specify those methods as events.

Note

A templated class or struct cannot contain events.

Requirements

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

For more information, see Attribute Contexts.

See also

Compiler attributes
event_receiver
__event
__hook
__unhook
Class attributes