How can I inform the implementor of my Interface that the "path" parameter represents a folder?

Question

I am about to define an interface in my application that plug-in writers can implement to provide user-defined "export" capabilities. It'll look something like this:

public interface IFooExporter
{
    void ExportFoo(Foo foo, string path);
}

However, I need to let the plug-in writers know (explicitly, not just in documentation) that "path" represents a folder, not a filename. It's their responsibility to create the files as part of the export process.

What's the best way to enforce that a path is a folder and not a filename? My best guess right now is to use DirectoryInfo instead of string:

public interface IFooExporter
{
    void ExportFoo(Foo foo, DirectoryInfo folder);
}

Is that a good solution, or are there pitfalls I'm not aware of with passing DirectoryInfo instances around?

Answer 1

Use XML comments, they will show up in Visual Studio's Intellisense popup.

/// <summary>
/// Type in the text you want to appear
/// </summary>

Answer 2

Name your variable more explicitly. Is it merely a path? You're saying no it is not, but you're still leaving it with a generic name. Name it folderPath and there will be less confusion and less need to explicitly communicate this to implementers.

Answer 3

Because you are not implementing the solution, then I agree with you solution of using the DirectoryInfo as a parameter. If you specify a string then there is no way to stop any string being passed.