/// <summary>
/// Asynchronously registers an anonymous command handler for the specified type of command.
/// </summary>
/// <typeparam name="TCommand">The type of command.</typeparam>
/// <param name="commandDispatcher">The command dispatcher.</param>
/// <param name="handler">The command handler that shall be registered.</param>
/// <returns>
/// A <see cref="IHandlerRegistration"/> representing the asynchronous operation.
/// The <see cref="IHandlerRegistration"/> cancels the handler registration if completed.
/// </returns>
/// <exception cref="ArgumentNullException">Thrown if either <paramref name="commandDispatcher"/> or <paramref name="handler"/> is null.</exception>
public static Task <IHandlerRegistration <ICommandHandler <TCommand> > > OnCommand <TCommand>(this ICommandDispatcher commandDispatcher, Func <TCommand, Task <ICommandResult> > handler) // TODO: Correct xml-comments
{
if (commandDispatcher == null)
{
throw new ArgumentNullException(nameof(commandDispatcher));
}
if (handler == null)
{
throw new ArgumentNullException(nameof(handler));
}
return(commandDispatcher.RegisterAsync(new AnonymousCommandHandler <TCommand>(handler)));
}