event_source

Article
2018-01-03

The latest version of this topic can be found at event_source.

Creates an event source.

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. You must 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 is 4 bytes of storage (minimum) for all events in a class or optimize=speed (the default) to indicate that there is 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 should not 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 is 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

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

For more information, see Attribute Contexts.

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