DirectoryCatalog Class

You can use a DirectoryCatalog object to parse the contents of a designated directory. Any attributed parts contained in dynamic link library (DLL) files are extracted and made available through the catalog.To restrict parsing to specific DLLs, you can specify a search pattern by using the same syntax as the Directory.GetFiles method.

Caution
The designated directory should not allow access to non-administrators. For example, using a folder that contains temporary Internet files could create vulnerabilities in your application.

The following example creates a DirectoryCatalog object that searches the directory the application runs from for parts. It uses a simple import to test the catalog. To fulfill this import, a DLL in the directory must have a matching export, as illustrated in the second code block.

public class Test2
{
    [Import]
    public Test1 data { get; set; }
}

class Program
{
    static void Main(string[] args)
    {
        DirectoryCatalog catalog = new DirectoryCatalog(".");
        CompositionContainer container = new CompositionContainer(catalog);
        Test2 test = new Test2();
        container.SatisfyImportsOnce(test);
        Console.WriteLine(test.data.data);
        Console.ReadLine();
    }
}

To create the matching export, the following code must be in a DLL file. To create a DLL file in Visual Studio, add a new project of the type "Class Library" to your solution, and place this code in it.

[Export]
public class Test1
{
    public String data = "The data!";
}

.NET Framework

.NET Framework Client Profile

Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

Reference