/// <summary>
/// Retrieves the extension specified by a given type, <typeparamref name="T"/>, from a given actor system.
/// If the extension does not exist within the actor system, then the extension specified by <paramref name="extensionId"/>
/// is registered to the actor system.
/// </summary>
/// <typeparam name="T">The type associated with the extension to retrieve.</typeparam>
/// <param name="system">The actor system from which to retrieve the extension or to register with if it does not exist.</param>
/// <param name="extensionId">The type of the extension to register if it does not exist in the given actor system.</param>
/// <returns>The extension retrieved from the given actor system.</returns>
public static T WithExtension <T>(this ActorSystem system, Type extensionId) where T : class, IExtension
{
if (system.HasExtension <T>())
{
return(system.GetExtension <T>());
}
else
{
return((T)system.RegisterExtension((IExtensionId)Activator.CreateInstance(extensionId)));
}
}
/// <summary>
/// Retrieves the extension specified by a given type, <typeparamref name="T"/>, from a given actor system.
/// If the extension does not exist within the actor system, then the extension specified by <typeparamref name="TI"/>
/// is registered to the actor system.
/// </summary>
/// <typeparam name="T">The type associated with the extension to retrieve.</typeparam>
/// <typeparam name="TI">The type associated with the extension to retrieve if it does not exist within the system.</typeparam>
/// <param name="system">The actor system from which to retrieve the extension or to register with if it does not exist.</param>
/// <returns>The extension retrieved from the given actor system.</returns>
public static T WithExtension <T, TI>(this ActorSystem system) where T : class, IExtension
where TI : IExtensionId
{
if (system.HasExtension <T>())
{
return(system.GetExtension <T>());
}
else
{
return((T)system.RegisterExtension((IExtensionId)Activator.CreateInstance(typeof(TI))));
}
}