Question

There is a possibility I’m not understanding how it’s supposed to work.

Where I start my app I do this:

IUnityContainer container = new UnityContainer();
container.RegisterInstance<IUnityContainer>(container);

//MainWindow
container.RegisterType<Window, MainWindow>();

//Services
container.RegisterType<IWindowManager, WindowManager>();

//Workspaces
container.RegisterType<WorkspaceViewModel, CompanyWorkspace>("Company");
container.RegisterType<WorkspaceViewModel, DivisionWorkspace>("Division")
//More of this
container.RegisterType<IWorkspaceFactory, WorkspaceFactory>();

Window window = container.Resolve<Window>();
window.DataContext = container.Resolve<ViewModel.MainWindowViewModel>();
window.Show();

My MainWindowViewModel gets resolved and here is it’s constructor

public MainWindowViewModel(IWorkspaceFactory workspaceFactory, IWindowManager windowManager)
    {
        _workspaceFactory = workspaceFactory;
        _windowManager = windowManager;
        _windowManager.Changed += new EventHandler(DialogChanged);
        ControlPanel = new ListCommandsViewModel();
        foreach (string s in _workspaceFactory.GetWorkspaceList())
        {
            ControlPanel.List.Add(new CommandViewModel(s, new RelayCommand<string>(OpenWorkspace)));
        }
    }

Notice that I subscribe to a event in the windowManager. WorkspaceFactory and WindowManager should are resolved here by Unity so instances of them are created.

Here is a implmentation of IWorkspaceFactory:

public class WorkspaceFactory : IWorkspaceFactory
{
    private IUnityContainer _container;

    public WorkspaceFactory(IUnityContainer container)
    {
        _container = container;
    }

    public ViewModel.WorkspaceViewModel GetWorkspace(string workspace)
    {
        return _container.Resolve<WorkspaceViewModel>(workspace);
    }

    public ICollection<string> GetWorkspaceList()
    {
        return _container.Registrations.Where(r => r.RegisteredType == typeof(WorkspaceViewModel)).Select(r => r.Name).ToList();
    }

}

As I registered the original container as a instance it should be what is passed into the factory. So I’m letting the same Container resolve the workspace that grabs IWindowsManager as a ctro parameter. So it should be getting the sama instance as the MainWindowViewModel got right?

But if I fire off the event from inside the workspace the MainView never gets notified, in actuality the Changed event is empty like this is a seperate instance of IWindowManager.

How may that be?

Am I totally off, I was under the impression that if you don’t define a LifeTime for types in containers you alwasy get the same instance.

Answer 1

Sorry, but I think you are off – if Unity is like AutoFac then the default behaviour will be “new instance per request”.

This is certainly what the docs look like “It will create a new instance of the registered, mapped, or requested type each time” – see http://msdn.microsoft.com/en-us/library/cc440953.aspx

To correct this, provide a LifetimeManager when you Register the type – e.g. ContainerControlledLifetimeManager (see http://msdn.microsoft.com/en-us/library/cc440953.aspx)