Will this coding style result in a memory leak

Question

Following the MVVM pattern I'm trying to wire up the display of a child window by the View in response to a request from the View Model.

Using the MVVM-Light Messenger the View will Register for the request to display the child window in the constructor of the View as so:

InitializeComponent();
Messenger.Default.Register<EditorInfo>(this, (editorData) =>
{
    ChildWindow editWindow = new EditWindow();
    editWindow.Closed += (s, args) =>
    {
        if (editWindow.DialogResult == true)
            // Send data back to VM
        else
           // Send 'Cancel' back to VM
   };

   editWindow.Show();
});

Does subscribing to the ChildWindow Closed event using a Lambda cause problems for garbage collection. Or put it another way, when (if ever) will the editWindow become unreferenced and so a candidate for garbage collection.

Answer 1

editWindow will keep a reference to this, but nothing will have a reference to editWindow, so it will eventually be garbage collected, and the reference to this will be discarded. So it shouldn't cause any memory leak...

If you want to be sure there will be no problem, you can unsubscribe from the event:

InitializeComponent();
Messenger.Default.Register<EditorInfo>(this, (editorData) =>
{
    ChildWindow editWindow = new EditWindow();
    EventHandler handler = (s, args) =>
    {
        editWindow.Closed -= handler;
        if (editWindow.DialogResult == true)
            // Send data back to VM
        else
           // Send 'Cancel' back to VM
   };

   editWindow.Closed += handler;

   editWindow.Show();
});