public static IEnumerable <KeyValuePair <Type, M> > GetExportTypesWithMetadata <T, M>(
this CompositionContainer mefcontainer)
where T : class where M : class
{
// need to examine each type to see if they have the correct export attribute and metadata
foreach (var type in mefcontainer.GetExportTypes <T>())
{
// should just be one if more than one will throw exception
// metadata or export attribute has to implement the interface
var metadataAttribute =
type.GetCustomAttributes()
.SelectMany(
a =>
a.GetType()
.GetCustomAttributes()
.OfType <MetadataAttributeAttribute>()
.Concat <Attribute>(new[] { a }.OfType <ExportAttribute>()))
.OfType <M>().SingleOrDefault();
// if we found the correct metadata
if (metadataAttribute != null)
{
// return the lazy factory
yield return(new KeyValuePair <Type, M>(type, metadataAttribute));
}
}
}
/// <summary>
/// Gets all types within the <see cref="CompositionContainer" />'s <see cref="CompositionContainer.Catalog" />
/// which implement the specified <paramref name="type" />.
/// </summary>
/// <param name="container">The container.</param>
/// <param name="type">The type.</param>
/// <returns>Enumeration of derived / implementing <see cref="Type" />s.</returns>
public static IEnumerable <Type> GetExportTypesThatImplement(this CompositionContainer container, Type type)
{
return(container.GetExportTypes()
.Where(typePart => typePart.IsAssignableToType(type)).ToList());
}
