/// <summary>
/// Implementation of <see cref="ITargetContainer.RegisterContainer(Type, ITargetContainer)" />
/// </summary>
/// <param name="type"></param>
/// <param name="container"></param>
/// <remarks>This container implementation actually stores containers against the types that targets are registered
/// against, rather than simply storing a dictionary of targets. This method allows you to add your own containers
/// against type (instead of the default, which is <see cref="TargetListContainer"/>) so you can plug in some advanced
/// behaviour into this container.
///
/// For example, decorators are not actually <see cref="ITarget"/> implementations but specialised <see cref="ITargetContainer"/>
/// instances into which the 'standard' targets are registered.</remarks>
public virtual void RegisterContainer(Type type, ITargetContainer container)
{
if (type == null)
{
throw new ArgumentNullException(nameof(type));
}
if (container == null)
{
throw new ArgumentNullException(nameof(container));
}
this._targetContainers.TryGetValue(type, out ITargetContainer existing);
// if there is already another container registered, we attempt to combine the two, prioritising
// the new container over the old one but trying the reverse operation if that fails.
if (existing != null)
{
// ask the 'new' one how it wishes to be combined with the other or, if that doesn't support
// combining, then try the existing container and see if that can.
// If neither can (NotSupportedException is expected here) then this
// operation fails.
try
{
this._targetContainers[type] = container.CombineWith(existing, type);
}
catch (NotSupportedException)
{
try
{
this._targetContainers[type] = existing.CombineWith(container, type);
}
catch (NotSupportedException)
{
throw new ArgumentException($"Cannot register the container because a container has already been registered for the type {type} and neither container supports the CombineWith operation");
}
}
}
else // no existing container - simply add it in.
{
this._targetContainers[type] = container;
}
}