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On a class, specifies the COM object's source interfaces for connection points. On a property or method, indicates that the member returns an object or VARIANT that is a source of events.

[ source(
) ]


One or more interfaces that you specify when you apply the source attribute to a class. This parameter is not used when source is applied to a property or method.

Attribute Context

Applies to class, struct, interface
Repeatable No
Required attributes coclass (when applied to class or struct)
Invalid attributes None

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


The source C++ attribute has the same functionality as the source MIDL attribute.

You can use the default attribute to specify the default source interface for an object.


// cpp_attr_ref_source.cpp
// compile with: /LD
#include "windows.h"
#include "unknwn.h"

[object, uuid(11111111-1111-1111-1111-111111111111)]
__interface b
   [id(0), propget, bindable, displaybind, defaultbind, requestedit]
   HRESULT get_I([out, retval]long *i);

[object, uuid(11111111-1111-1111-1111-111111111131)]
__interface c
   [id(0), propget, bindable, displaybind, defaultbind, requestedit] 
   HRESULT et_I([out, retval]long *i);

[coclass, default(c), uuid(11111111-1111-1111-1111-111111111132)]
class N : public b

[coclass, source(c), default(b, c), uuid(11111111-1111-1111-1111-111111111133)]
class NN : public b

See Also

IDL Attributes | Class Attributes | Method Attributes | coclass | Attributes Samples