如何使变量的值跟踪另一个变量的值

Question

这是我现在拥有的一个非常简化的示例：

public static class Settings
{
    public static TH th;
}

public partial class PhrasesFrame
{
    private void SetC1Btn()
    {
        var a = (int)Settings.th;
        vm.C1BtnLabelTextColor = phrase.C1 == true ?
            Styles.A[(int)Settings.th] :
            Styles.A[(int)Settings.th];
    }

我想将其替换为：

public partial class PhrasesFrame
{
    // The value of Settings.th can change at any time

    // I want the value of id to change when the 
    // value of (int)Setting.th changes. The way
    // it's coded now I realize it's just a one
    // time assignment

    var id = (int)Settings.th; 

    private void SetC1Btn()
    {
        var a = (int)Settings.th;
        vm.C1BtnLabelTextColor = phrase.C1 == true ?
            Styles.A[id] :
            Styles.A[id];
    }

Answer 1

这个Settings 类实现了一个自定义EventHandler (SettingsChangedEventHandler)，用于通知其订阅者的属性更改：
您可以设置一个更复杂的自定义 SettingsEventArgs 来传递不同的值。

更改公共THProperty 属性值引发事件：

public static class Settings
{
    public delegate void SettingsChangedEventHandler(object sender, SettingsEventArgs e);
    public static event SettingsChangedEventHandler SettingsChanged;

    private static TH th;
    private static int m_Other;

    public class SettingsEventArgs : EventArgs
    {
        public SettingsEventArgs(TH m_v) => THValue = m_v;
        public TH THValue { get; private set; }
        public int Other => m_Other;
    }

    public static void OnSettingsChanged(SettingsEventArgs e) => 
        SettingsChanged?.Invoke("Settings", e);

    public static TH THProperty
    {
        get => th;
        set { th = value; OnSettingsChanged(new SettingsEventArgs(th)); }
    }
}

PhrasesFrame 类可以像往常一样订阅事件：

public partial class PhrasesFrame
{
    private TH id;

    public PhrasesFrame()
    {
        Settings.SettingsChanged += this.SettingsChanged;
    }

    private void SetC1Btn()
    {
        var a = (int)this.id;
        //Other operations
    }

    private void SettingsChanged(object sender, Settings.SettingsEventArgs e)
    {
        this.id = e.THValue;
        SetC1Btn();
    }
}

Answer 2

如何将一个动作添加到您的静态设置类，并从设置器触发该动作？

我使用 int 代替您的 TH 对象，但我相信您可以修改以下示例。

在这里测试：https://dotnetfiddle.net/ItaMhL

using System;
public class Program
{
    public static void Main()
    {
        var id = (int)Settings.th;
        Settings.action = () => id = Settings.th;
        Settings.th = 123;
        Console.WriteLine(id);

        Settings.th = 234;
        Console.WriteLine(id);
    }

    public static class Settings
    {
        private static int _th;
        public static int th
        {
            get{return _th;}
            set{
                _th = value;
                action();}
        }

        public static Action action;
    }
}