In which window should I instantiate my object? - wpf

Question

My WPF application has multiple windows:
MainWindow
ChildWindow1
Childwindow2
I instantiate the children from MainWindow by...
public partial class MainWindow : Window
{
ChildWindow1 CW1;
ChildWindow2 CW2;
public MainWindow()
{
InitializeComponent();
}
private void btnButton1_Click(object sender, RoutedEventArgs e)
{
CW1 = new ChildWindow1();
CW1.Show();
CW1.Owner = this;
CW2 = new ChildWindow2();
CW2.Show();
CW2.Owner = this;
}
}
Awesome!
But here's where I run into trouble: I have a non-UI class that I need to instantiate.
public class MyClass
{
public void DoSomething()
{
//Do something here
}
}
The object of that class should "live" inside ChildWindow1, because that's where it logically belongs. So, I instantiate it inside ChildWindow1 like so:
public partial class ChildWindow1 : Window
{
public MyClass MyObject = new MyClass();
public ChildWindow1()
{
InitializeComponent();
}
}
But eventually comes a point where ChildWindow2 needs to interact with the object in ChildWindow1:
Call the 'DoSomething()' method of the object in Childwindow1.
Subscribe to an event raised by the object in ChildWindow1
I can do all that from the main window, because it owns the children, but I want the children to be able to interact directly.
Am I violating a design principle by allowing CW1 <--> CW2 interaction?
How else would you get them to interact if not by calling methods or subscribing to events?
Thanks to all here, for providing this awesome learning resource! Much appreciated!

Answer 1

Make this the instance of MyClass both public and static, to access it from almost anywhere because that should be accessed based on a certain instance of window.
If you wanna access a variable from any window, either make it static or call it based on an instance of that window like:
public partial class ChildWindow1 : Window
{
public static MyClass MyObject = new MyClass();
public ChildWindow1()
{
InitializeComponent();
}
}
access like this CW1.MyObject