How to add connection points to an object?

To add a connection point to a control or object.

1. A dispinterface should be defined in the library block of the.idl file. The dispinterface will already be built if support for connection points was enabled when the control was created using the ATL Control Wizard. 

2. If connection point support was not enabled when the control was created, you would need to manually add the dispinterface to the.idl file. 

Here is an illustration of a dispinterface. While dispatch interfaces are unnecessary for outgoing interfaces, many scripting languages like VBScript and JScript do. Hence this example uses two of them:

3. In the project.idl file, add the dispinterface as the interface for the object. When you create the control, the ATI control wizard will create the default source entry if you enable the support for connecting points.

The following codes are to be used for manually adding this to the entry:

coclass Buddy
{
   [default] interface IBuddy;
   [default,source] dispinterface DBuddyEvents;
};

4. Class view will be used to add methods and properties to the event interface. It can be done by Right-clicking on class in the class view, going to ADD, and clicking Add Connecting Point.

5. Select the project's interfaces in the Implement Connection Point Wizard's Source Interfaces list box. If you select a control interface and click OK

To reuse the connection point interface defined in another type of library.

1. Right-click a class in Class View that implements the BEGIN_COM_MAP macro, select Add from the shortcut menu, and then choose Add Connection Point.
2. Click Add after selecting a type library and an interface in type library's Implement Connection Point Wizard.
3. The object's dispinterface from the.idl file
4. Use the importlib command on a library of that type.

Frequently Asked Questions

What is a template in OOP?

A template is a section of code that may be duplicated and altered to suit a particular situation.

What does DLL stand for?

When necessary, larger applications might load a collection of smaller programs known as a dynamic link library (DLL) to carry out specialized functions.

What are ATL applications?

ActiveX controls are frequently created using the Active Template Library (ATL), a wrapper library that makes COM development easier.

What are COM and ATL?

Microsoft created the Active Template Library (ATL), a collection of template-based C++ classes, to make designing Component Object Model (COM) objects easier.

What are C++ templates?

In C++, a template is a design pattern or recipe for developing a generic class or function.

Conclusion

This blog has extensively discussed adding connection points to an object. We hope this blog has helped you enhance your knowledge about adding a connection point to a control or object and reusing a connection point interface defined in another library type.

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