From f265b48e8a4f49f6599a34858b4e06997fabf2af Mon Sep 17 00:00:00 2001
From: "DESKTOP-3BO4HSG\\ksat" <zggsong@foxmail.com>
Date: Mon, 3 Apr 2023 15:22:20 +0800
Subject: [PATCH] chore: optimized singleton pattern is lazy and thread-safe

---
 STranslate/Helper/ConfigHelper.cs  |  4 +---
 STranslate/Helper/MvvmHelper.cs    | 12 ++++++++++++
 STranslate/Helper/SqliteHelper.cs  |  1 +
 STranslate/ViewModel/MainVM.cs     |  4 ++--
 STranslate/ViewModel/SettingsVM.cs |  4 ++--
 5 files changed, 18 insertions(+), 7 deletions(-)

diff --git a/STranslate/Helper/ConfigHelper.cs b/STranslate/Helper/ConfigHelper.cs
index 910c04e..852aee9 100644
--- a/STranslate/Helper/ConfigHelper.cs
+++ b/STranslate/Helper/ConfigHelper.cs
@@ -10,7 +10,7 @@ using System.Threading.Tasks;
 
 namespace STranslate.Helper
 {
-    public class ConfigHelper
+    public class ConfigHelper : Singleton<ConfigHelper>
     {
         public T ReadConfig<T>()
         {
@@ -54,7 +54,5 @@ namespace STranslate.Helper
         /// </summary>
         private static string _ApplicationData => $"{Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData)}\\{_AppName}";
         private static readonly string _AppName = Path.GetFileNameWithoutExtension(Assembly.GetEntryAssembly().Location);
-        private static ConfigHelper _Instance;
-        public static ConfigHelper Instance { get => _Instance ?? (_Instance = new ConfigHelper()); }
     }
 }
diff --git a/STranslate/Helper/MvvmHelper.cs b/STranslate/Helper/MvvmHelper.cs
index 8919b8f..2400018 100644
--- a/STranslate/Helper/MvvmHelper.cs
+++ b/STranslate/Helper/MvvmHelper.cs
@@ -5,6 +5,18 @@ using System.Runtime.CompilerServices;
 
 namespace STranslate.Helper
 {
+    /// <summary>
+    /// Generate Singleton
+    /// </summary>
+    /// <typeparam name="T"></typeparam>
+    public class Singleton<T> where T : class
+    {
+        private static readonly Lazy<T> _instance = new Lazy<T>(()
+            => Activator.CreateInstance(typeof(T), true) as T, true);
+
+        public static T Instance => _instance.Value;
+    }
+
     /// <summary>
     /// 通知
     /// </summary>
diff --git a/STranslate/Helper/SqliteHelper.cs b/STranslate/Helper/SqliteHelper.cs
index ae59ac0..b4ae1fe 100644
--- a/STranslate/Helper/SqliteHelper.cs
+++ b/STranslate/Helper/SqliteHelper.cs
@@ -9,6 +9,7 @@ using System.Threading.Tasks;
 
 namespace STranslate.Helper
 {
+    //https://github.com/praeclarum/sqlite-net
     public class SqliteHelper : IDisposable
     {
         public SqliteHelper()
diff --git a/STranslate/ViewModel/MainVM.cs b/STranslate/ViewModel/MainVM.cs
index d7662c4..53e0896 100644
--- a/STranslate/ViewModel/MainVM.cs
+++ b/STranslate/ViewModel/MainVM.cs
@@ -474,8 +474,8 @@ namespace STranslate.ViewModel
         /// </summary>
         public MainWindow Mainwin;
 
-        private static MainVM _instance;
-        public static MainVM Instance => _instance ?? (_instance = new MainVM());
+        private static Lazy<MainVM> _instance = new Lazy<MainVM>(() => new MainVM());
+        public static MainVM Instance => _instance.Value;
 
         public Hotkeys NHotkeys;
         private bool IsTopmost { get; set; }
diff --git a/STranslate/ViewModel/SettingsVM.cs b/STranslate/ViewModel/SettingsVM.cs
index ab8a920..0b183ef 100644
--- a/STranslate/ViewModel/SettingsVM.cs
+++ b/STranslate/ViewModel/SettingsVM.cs
@@ -110,8 +110,8 @@ namespace STranslate.ViewModel
         public ICommand EscCmd { get; private set; }
 
 
-        private static SettingsVM _instance;
-        public static SettingsVM Instance => _instance ?? (_instance = new SettingsVM());
+        private static Lazy<SettingsVM> _instance = new Lazy<SettingsVM>(() => new SettingsVM());
+        public static SettingsVM Instance => _instance.Value;
 
         /// <summary>
         /// 是否开机自启