How to subscribe to an event inside a facade class

Question

I have two projects 1: windows forms project and 2: a business logic project that recursively walks the file system looking for specific files.

I want the windows project to subscribe to an event buried in a class called recurse. The problem I have is the instance of the recurse class is instantiated inside a facade class in the business logic project.

The windows forms project calls the business logic via a facade like so:

        FileAnalyzerFacade fileAnalyzerFacade = new FileAnalyzerFacade();
        fileAnalyzerFacade.WalkDirectory(path, searchFilter));

In project 2 the FileAnalyzerFacade() creates an instance of the Recurse() class. The Recurse() class raises an event when it finds a file. So the windows form knows nothing about the Recurse() class only the outer facade FileAnalyzerFacade().

The facade has the following subscription:

recurse.FileFound += new FilePropertyEventHandler(analyzeFile);

When the event is fired the analyzeFile() is run.

This is all fine as the FileAnalyzerFacade() creates the instance of the recurse class. How can I get the windows project to subscribe to the event raised inside the recurse class?

Answer 1

Actually, you are trying to break Law of Demeter here. Therefore I suggest you to review your design. But the simplest option would be to expose similar event in your Facade class, or provide an additional delegate parameter to the WalkDirectory method.