How can I save global application variables in WPF?

Question

In WPF, where can I save a value when in one UserControl, then later in another UserControl access that value again, something like session state in web programming, e.g.:

UserControl1.xaml.cs:

Customer customer = new Customer(12334);
ApplicationState.SetValue("currentCustomer", customer); //PSEUDO-CODE

UserControl2.xaml.cs:

Customer customer = ApplicationState.GetValue("currentCustomer") as Customer; //PSEUDO-CODE

ANSWER:

Thanks, Bob, here is the code that I got to work, based on yours:

public static class ApplicationState
{
    private static Dictionary<string, object> _values =
               new Dictionary<string, object>();
    public static void SetValue(string key, object value)
    {
        if (_values.ContainsKey(key))
        {
            _values.Remove(key);
        }
        _values.Add(key, value);
    }
    public static T GetValue<T>(string key)
    {
        if (_values.ContainsKey(key))
        {
            return (T)_values[key];
        }
        else
        {
            return default(T);
        }
    }
}

To save a variable:

ApplicationState.SetValue("currentCustomerName", "Jim Smith");

To read a variable:

MainText.Text = ApplicationState.GetValue<string>("currentCustomerName");

Answer 1

Could just store it yourself in a static class or repository that you can inject to the classes that need the data.

Answer 2

You can expose a public static variable in App.xaml.cs file and then access it anywhere using App class..

Answer 3

Something like this should work.

public static class ApplicationState { 
    private static Dictionary<string, object> _values =
               new Dictionary<string, object>();
    public static void SetValue(string key, object value) {
        _values.Add(key, value);
    }
    public static T GetValue<T>(string value) {
        return (T)_values["value"];
    }
}

Answer 4

The Application class already has this functionality built in.

// Set an application-scope resource
Application.Current.Resources["ApplicationScopeResource"] = Brushes.White;
...
// Get an application-scope resource
Brush whiteBrush = (Brush)Application.Current.Resources["ApplicationScopeResource"];