public class CSLExportProvider : ExportProvider
{
    private IServiceLocator serviceLocator;
    private IDictionary<string, Type> contractMapping;
    
    public CSLExportProvider(IServiceLocator serviceLocator)
    {
        this.contractMapping = new Dictionary<string, Type>();
        this.serviceLocator = serviceLocator;
    }
 
    //The IoC container needs to call this in order to tell MEF how to call it back.
    public void RegisterType(Type type)
    {
       contractMapping.Add(AttributedModelServices.GetContractName(type), type);
    }
 
    //Returns a lazy reference to a service coming out of the IoC
    protected override System.Collections.Generic.IEnumerable<System.ComponentModel.Composition.Primitives.Export> GetExportsCore(System.ComponentModel.Composition.Primitives.ImportDefinition definition, AtomicComposition atomicComposition)
    {
        if (definition.ContractName != null)
        {
            Type contractType;
            if(contractMapping.TryGetValue(definition.ContractName, out contractType))
            {
                if (definition.Cardinality == ImportCardinality.ExactlyOne || definition.Cardinality == ImportCardinality.ExactlyOne)
                {
                    var export = new Export(definition.ContractName, () => serviceLocator.GetInstance(contractType));
                    return new List<Export> { export };
                }
                
            }
        }
        return Enumerable.Empty<Export>();
    }
}
 
public class CSLExportProviderExtension : UnityContainerExtension
{
    private CSLExportProvider exportProvider;
 
    public CSLExportProviderExtension(CSLExportProvider exportProvider)
    {
        this.exportProvider = exportProvider;
    }
 
    protected override void Initialize()
    {
        this.Context.Registering += new EventHandler<RegisterEventArgs>(Context_Registering);
        this.Context.RegisteringInstance += new EventHandler<RegisterInstanceEventArgs>(Context_RegisteringInstance);
    }
 
    void Context_RegisteringInstance(object sender, RegisterInstanceEventArgs e)
    {
        exportProvider.RegisterType(e.RegisteredType);
    }
 
 
    void Context_Registering(object sender, RegisterEventArgs e)
    {
        exportProvider.RegisterType(e.TypeFrom);
    }
}