Resolution status in DryIoc container

Question

Is it possible in DryIoc container to figure out whether some singleton has been instantiated?

For instance

var container = new Container();
container.Register<IApplicationContext, ApplicationContext>( Reuse.Singleton );

// var context = container.Resolve<IApplicationContext>(); 

if ( container.IsInstantiated<IApplicationContext>() ) // Apparently this does not compile
{
  // ...
}
// OR
if ( container.IsInstantiated<ApplicationContext>() )
{
  // ...
}

Answer 1

There is no way at the moment and no such feature planned. You may create an issue to request this.

But I am wandering why it is needed. Cause singleton provides a guarantee to be created only once, so you may not worry or check for double creation.

Is it for something else?

Update

OK, in DryIoc you may register a "decorator" to control and provide information about decoratee creation, here is more on decorators:

[TestFixture]
public class SO_IsInstantiatedViaDecorator
{
    [Test]
    public void Test()
    {
        var c = new Container();
        c.Register<IService, X>(Reuse.Singleton);

        c.Register<XProvider>(Reuse.Singleton);

        c.Register<IService>(
            Made.Of(_ => ServiceInfo.Of<XProvider>(), p => p.Create(Arg.Of<Func<IService>>())),
            Reuse.Singleton,
            Setup.Decorator);

        c.Register<A>();

        var x = c.Resolve<XProvider>();
        Assert.IsFalse(x.IsCreated);

        c.Resolve<A>();

        Assert.IsTrue(x.IsCreated);
    }

    public interface IService { }
    public class X : IService { }

    public class A
    {
        public A(IService service) { }
    }

    public class XProvider
    {
        public bool IsCreated { get; private set; }
        public IService Create(Func<IService> factory)
        {
            IsCreated = true;
            return factory();
        }
    }
}

This example also illustrates how powerful is composition of DryIoc decorators and factory methods.