Example of chaining supervision deciders in Akka.NET.

AkkaDeciderChaining.cs

/// <summary>
///		Extension methods for Akka's <see cref="IDecider">decider</see>s.
/// </summary>
public static class DeciderChaining
{
	/// <summary>
	///		Create a new <see cref="LocalOnlyDecider"/> that first calls the <paramref name="decider"/>, but then calls <paramref name="escalateToDecider"/> if the original <paramref name="decider"/> returns <see cref="Directive.Escalate"/>.
	/// </summary>
	/// <param name="decider">
	///		The original <see cref="IDecider"/>.
	/// </param>
	/// <param name="escalateToDecider">
	///		The <see cref="LocalOnlyDecider"/> to call if the original <paramref name="decider"/> returns <see cref="Directive.Escalate"/>.
	/// </param>
	/// <returns>
	///		The new (composite) decider.
	/// </returns>
	public static LocalOnlyDecider Then(this IDecider decider, Func<Exception, Directive> escalateToDecider)
	{
		if (decider == null)
			throw new ArgumentNullException(nameof(decider));
	
		if (escalateToDecider == null)
			throw new ArgumentNullException(nameof(escalateToDecider));
	
		return decider.Then(
			Decider.From(escalateToDecider)
		);
	}
	
	/// <summary>
	///		Create a new <see cref="LocalOnlyDecider"/> that first calls the <paramref name="decider"/>, but then calls <paramref name="escalateToDecider"/> if the original <paramref name="decider"/> returns <see cref="Directive.Escalate"/>.
	/// </summary>
	/// <param name="decider">
	///		The <see cref="LocalOnlyDecider"/>.
	/// </param>
	/// <param name="escalateToDecider">
	///		The <see cref="IDecider">decider</see> to call if the original <paramref name="decider"/> returns <see cref="Directive.Escalate"/>.
	/// </param>
	/// <returns>
	///		The new (composite) decider.
	/// </returns>
	public static LocalOnlyDecider Then(this IDecider decider, IDecider escalateToDecider)
	{
		if (decider == null)
			throw new ArgumentNullException(nameof(decider));
	
		if (escalateToDecider == null)
			throw new ArgumentNullException(nameof(escalateToDecider));
	
		return Decider.From(exception =>
		{
			Directive directive = decider.Decide(exception);
	
			return directive == Directive.Escalate ? escalateToDecider.Decide(exception) : directive;
		});
	}
}