/// <summary>
/// This method provides an implementation for an <see cref="IComposer{TTarget}"/>
/// to handle this event. This checks the <see cref="Participant"/>, and the
/// <see cref="Request"/>, and will invoke your <paramref name="composer"/>
/// as specified.
/// </summary>
/// <typeparam name="T">Your <paramref name="composer"/>
/// actual (covariant) type.</typeparam>
/// <param name="composer">Not null.</param>
/// <returns>True if any method was invoked on the <paramref name="composer"/>.
/// False if not invoked.</returns>
/// <exception cref="ArgumentNullException"></exception>
public bool Handle <T>(IComposer <T> composer)
where T : TTarget
{
if (composer == null)
{
throw new ArgumentNullException(nameof(composer));
}
if (Participant == null)
{
return(false);
}
IComposer <TTarget> targetComposer = composer as IComposer <TTarget>;
switch (Request)
{
case ParticipantRequest.Add:
if (targetComposer != null)
{
targetComposer.Participate(Participant);
return(true);
}
composer.ParticipateAs(Participant);
return(true);
case ParticipantRequest.AddOneTimeOnly:
if (targetComposer != null)
{
targetComposer.Participate(Participant, true);
return(true);
}
composer.ParticipateAs(Participant, true);
return(true);
case ParticipantRequest.Remove:
if (targetComposer != null)
{
targetComposer.Remove(Participant);
return(true);
}
composer.Remove(new VariantParticipant <TTarget, T>(Participant));
return(true);
}
return(false);
}