Adding an Event Using Attributes
Events allow an ActiveX control to communicate important information to its container. Using attributes, adding an event is a simple matter. For detailed information on adding and firing events from an ATL control, see Event Handling in COM.
Conclusion
In the past, implementing the standard features of an ActiveX control could be a tedious task. However, using the attributed programming model, the various wizards of Visual C++, and the Visual C++ compiler itself, implementing a basic ActiveX control now requires little effort, and makes use of code that has been tested and optimized by the Visual C++ team.
See Also
Concepts
Walkthrough: Creating an ActiveX Control with Attributes
Creating the ActiveX Control Project
Inserting the ATL Control Component