/// <summary>
/// Evaluates whether a candidate type is a provider type.
/// </summary>
/// <remarks>
/// The default implementation simply tests if the candidate type
/// is a qualified descendent of the TProv provider type.
/// <para>
/// Subclasses may add, or replace with, other conditions such as testing
/// for the presence of a particular class-level custom attribute or
/// testing for the presence of other features of the class definition
/// such as a qualifying constructor signature.
/// </para>
/// </remarks>
protected bool MatchProviderType(Type candidate)
{
return(MefExtensions.IsDescendentOf(candidate, typeof(TProv)));
}
/// <summary>
/// Evaluates whether a candidate type is a provider type.
/// </summary>
/// <remarks>
/// The default implementation simply tests if the candidate type
/// is a qualified descendent of the TExt provider type and is
/// decorated with a custom attribute of type TAtt.
/// </remarks>
protected bool MatchProviderType(Type candidate)
{
return(MefExtensions.IsDescendentOf(candidate, typeof(TExt)) &&
candidate.GetTypeInfo().GetCustomAttribute <TAtt>() != null);
}