Unity 2.0: How to use Resolve with ResolverOverride?

Question

I started doing more and more work with Unity. I notice that Resolver method takes a params argument ResolverOverride.

Can someone give me an example how I can use ResolverOverride or point me some other source where I can get more clues.

Answer 1

As you have noticed this is a new (and really cool feature) of the Unity 2. This feature let you

• pass parameters to constructor in the moment when you resolve the class. In unity 1 you can set only one value in the moment when you register type via new InjectionConstructor(...)

There is ParameterOverride : ResolverOverride

A ResolverOverride class that lets you override a named parameter passed to a constructor.

• same for dependencies with DependencyOverride : ResolverOverride

A class that overrides the value injected whenever there is a dependency of the given type, regardless of where it appears in the object graph.

• same for properties with PropertyOverride : ResolverOverride

A ResolverOverride that lets you override the value for a specified property.

Example

using System; using Microsoft.Practices.Unity;  namespace ConsoleApplication1 {     class Program {         static void Main(string[] args) {              var container = new UnityContainer();              //ParameterOverride example              container.RegisterType<IConcreteService, ConcreteService>(                 new InjectionConstructor(7) //Old way to pass value to constructor - not flexible.                                              //All resolved (without override which appears only in unity 2.0) classes will have val=7                 );              var service0 = container.Resolve<IConcreteService>();             Console.WriteLine(service0.Val); //prints 7              var service = container.Resolve<IConcreteService>(new ParameterOverride("val", 3));             Console.WriteLine(service.Val); // prints 3              var service2 = container.Resolve<IConcreteService>(new ParameterOverride("val", 5));             Console.WriteLine(service2.Val); // prints 5              Console.ReadLine();              //DependencyOverride example              var b0 = container.Resolve<B>(new DependencyOverride<IConcreteService>(new ConcreteService(42)));             Console.WriteLine(b0.Service.Val); //print 42             Console.WriteLine(b0.Service1.Val); //print 42              var b = container.Resolve<B>(new DependencyOverride<IConcreteService>(new ConcreteService(-42)));             Console.WriteLine(b.Service.Val); // print -42             Console.WriteLine(b.Service1.Val); // print -42              Console.ReadLine();              //PropertyOverride example               var b1 = container.Resolve<B>(new PropertyOverride("Service", new ConcreteService(42)),                  new PropertyOverride("Service1", new ConcreteService(-42)));             Console.WriteLine(b1.Service.Val); //print 42             Console.WriteLine(b1.Service1.Val); //print -42              Console.ReadLine();            }     }      public interface IConcreteService {         int Val { get; set; }     }     public class ConcreteService : IConcreteService {          public int Val { get; set; }          public ConcreteService(int val) {             Val = val;         }     }      public class B {         [Dependency]         public IConcreteService Service{ get; set; }          [Dependency]         public IConcreteService Service1 { get; set; }      } } 

Have no idea why does Google keeps silent about that.

Quotes are from Unity source code xml docs.