From 8a876a756ef115936d401c3aecf7c2d83981dd22 Mon Sep 17 00:00:00 2001
From: XMuli <xmulitech@gmail.com>
Date: Sat, 24 Dec 2022 01:30:52 +0800
Subject: [PATCH] feat: add Singleton Pattern

---
 Studio/DesignPatterns/Singleton.cpp |  1 +
 Studio/DesignPatterns/Singleton.h   | 23 ++++++++++++++++++++++-
 2 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/Studio/DesignPatterns/Singleton.cpp b/Studio/DesignPatterns/Singleton.cpp
index 69acca0..dbb7fcd 100644
--- a/Studio/DesignPatterns/Singleton.cpp
+++ b/Studio/DesignPatterns/Singleton.cpp
@@ -1 +1,2 @@
 #include "Singleton.h"
+ 
\ No newline at end of file
diff --git a/Studio/DesignPatterns/Singleton.h b/Studio/DesignPatterns/Singleton.h
index 11faed8..23c36ce 100644
--- a/Studio/DesignPatterns/Singleton.h
+++ b/Studio/DesignPatterns/Singleton.h
@@ -6,7 +6,7 @@
  ******************************************************************/
 #pragma once
 
-// 《Effective C++》提出了一种更优雅的单例模式实现，称为 Meyers' Singleton
+// 推荐使用 →《Effective C++》提出了一种更优雅的单例模式实现，称为 Meyers' Singleton
 class Singleton
 {
 public:
@@ -22,3 +22,24 @@ private:
     Singleton& operator=(const Singleton& obj) = delete;
 };
 
+//---------------------------------------------------------
+// 不推荐使用 → Eager Singleton 是线程安全的，但存在潜在问题 no-local static 对象在不同编译单元中的初始化顺序是未定义的
+class Singleton2
+{
+public:
+    static Singleton2& instance() {
+        return instan;
+    }
+
+private:
+    Singleton2() {};
+    ~Singleton2() {};
+    Singleton2(const Singleton2&) = delete;
+    Singleton2& operator=(const Singleton2&) = delete;
+
+private:
+    static Singleton2 instan;
+};
+
+Singleton2 Singleton2::instan;
+