Dependency Injection

This example uses Autofac however any DI component can be used using the approach demonstrated below.

Install Autofac

Install-Package Autofac

Implement IDependencyResolver (uses autofac)

class DependencyResolver : IDependencyResolver
{
    IContainer _container;

    public DependencyResolver()
    {
        var _builder = new ContainerBuilder();
        _builder.RegisterType<MyService>().As<IService>();
        _container = builder.Build();
    }

    public object GetService(Type serviceType)
    {
        using (var scope = _container.BeginLifetimeScope())
        {
            return scope.ResolveOptional(serviceType);
        }
    }

    public IEnumerable<object> GetServices(Type serviceType)
    {
        using (var scope = _container.BeginLifetimeScope())
        {
            var enumerableServiceType = typeof(IEnumerable<>).MakeGenericType(serviceType);
            var instance = scope.Resolve(serviceType);
            return (IEnumerable<object>)instance;
        }
    }
}

Create Rule

class UpdateTrackingNumber : Rule<Order>
{
    IService _service

    // Dependency Resolver resolves IService instance
    public ValidatePhoneNumberIs10Digits(IService service)
    {
        _service = service
    }

    public override IRuleResult Invoke()
    {
        _service.UpdateTrackingNumber();
        return null;
    }
}

Pass it to RuleEngine

Notice only the type of the rule is added to the rule engine rather than its instance

// Dependency Resolver resolves UpdateTrackingNumber instance 
var ruleEngine = RuleEngine<Order>.GetInstance(new Order(), new DependencyResolver());

ruleEngine.AddRule<UpdateTrackingNumber>();
ruleEngine.Execute()