Unity Container: use ContainerControlledLifetimeManager by default for "Resolve" method group

.net, dependency-injection, singleton, unity-container

Solution

I see where you are going with this. Interesting problem.

I think you can do what you are doing with a Unity Behavior Extension. Here's a great article on the design of Unity that describes the job of certain elements of Unity that a lot of people don't know about: http://msdn.microsoft.com/en-us/library/dd140062.aspx

The Unity Container basically uses a "strategy chain" when handling a resolve request. One of the strategies in the chain is the `LifetimeStrategy`.

The easiest thing to do would be to create a new strategy and insert it in the chain before the `LifetimeStrategy` so that when your strategy gets a chance to look at the type, it can register a ContainerControlledLifetimeManager for that type in the current container. It will get to the LifetimeStrategy and there will already be a ContainerControlledLifetimeManager registered for that type.

It might look like this:

public class MakeEverythingSingletonStrategy : BuilderStrategy
{
     public override void PreBuildUp(IBuilderContext context)
     {
          Type objectType = BuildKey.GetType(context.BuildKey);
          context.PersistentPolicies.Set<ILifetimePolicy>(
                  new SingletonLifetimePolicy(), 
                  context.BuildKey);

     }
}

You should be able to apply this configuration to the sub container using the `Configure<T>` method, passing in a configuration class that adds this new extension.

I found a good sample of someone on Stackoverflow implementing a custom BuilderStrategy:

Custom object factory extension for Unity

Problem

How to fill TODO to make this test pass? ``` class MyClass { } [Test] public void Singleton_by_default_test() { var parentContainer = GetUnityContainer(); var container = parentContainer.GetChildContainer(); // TODO: Add magic here (but do NOT explicitly register MyClass in container!) Assert.AreSame(container.Resolve<MyClass>(), container.Resolve<MyClass>()); } ``` Update: There is a way that uses inheritance. ``` public class SingletonContainer : UnityContainer { public override object Resolve(Type t, string name) { var obj = base.Resolve(t, name); RegisterInstance(t, name, obj, new ContainerControlledLifetimeManager()); return obj; } } ``` I am using container.GetChildContainer() to get container instance so this method does not suite me.

Original source