UWP 使用 x:Bind 监控全局变量

Question

I have an App that groups all the global variables in a single class. They are used over MANY classes in the App. (300+ variables, shortened for demo):

public class Vars
{
    public static string DateStr = "";
}

I want to use x:Bind to One-way bind the data to fields on a page:

<TextBlock x:Name="Local_Data" Text="{x:Bind local:Vars.DateStr, Mode=OneWay}" Style="{StaticResource TextBlockStyle1}"/>

OneTime binding seems to work OK. I can refresh the page and the DateStr reflects the new value.

I changed the Vars class definition to:

public class Vars : INotifyPropertyChanged
{

    private static string _DateStr = "hello";

    public static string DateStr
    {
        get { return _DateStr; }
        set
        {
            _DateStr = value;
            OnPropertyChanged();
        }
    }

    #region INotifyPropertyChanged Members

    public event PropertyChangedEventHandler PropertyChanged;

    /// <summary>
    /// Raises this object's PropertyChanged event.
    /// </summary>
    /// <param name="propertyName">The property that has a new value.</param>
    protected void OnPropertyChanged([CallerMemberName]string propertyName = null)
    {
        PropertyChangedEventHandler handler = this.PropertyChanged;
        if (handler != null)
        {
            var e = new PropertyChangedEventArgs(propertyName);
            handler(this, e);
        }
    }
    #endregion
}

When I try to build, I get the message:

An object reference is required for the non-static field, method, or property 'Vars.OnPropertyChanged(string)'

If I change it to:

    protected static void OnPropertyChanged([CallerMemberName]string propertyName = null)
    {
        PropertyChangedEventHandler handler = this.PropertyChanged;
        if (handler != null)
        {
            var e = new PropertyChangedEventArgs(propertyName);
            handler(this, e);
        }
    }

I get the message:

Keyword 'this' is not valid in a static property, static method, or static field initializer

I assume that it is something trivial that I am missing. What is the proper way to flag the data changing?

Thanks for your help. Dan

Answer 1

As the error message mentioned, the reason for your issue is that you are using Static modifier for the binding source property- Vars.DateStr . You just need to remove the Static modifier of the Vars.DateStr property.

  public  string DateStr
    {
        get { return _DateStr; }
        set
        {
            _DateStr = value;
            OnPropertyChanged("DateStr");
        }
    }