46 lines
1.3 KiB
C++
46 lines
1.3 KiB
C++
/*******************************************************************
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* Copyright (c) 2022~2023 XMuli All rights reserved.
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* GitHub: https://github.com/XMuli
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* Description: 单例模式 Singleton Pattern 的最优雅实现
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* Reference: https://zhuanlan.zhihu.com/p/37469260 单例介绍及好一篇
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******************************************************************/
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#pragma once
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// 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
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class Singleton
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{
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public:
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static Singleton& instance() {
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static Singleton instan;
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return instan;
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}
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private:
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Singleton() {};
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~Singleton() {};
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Singleton(const Singleton& obj) = delete;
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Singleton& operator=(const Singleton& obj) = delete;
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};
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//---------------------------------------------------------
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// 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
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class Singleton2
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{
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public:
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static Singleton2& instance() {
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return instan;
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}
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private:
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Singleton2() {};
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~Singleton2() {};
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Singleton2(const Singleton2&) = delete;
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Singleton2& operator=(const Singleton2&) = delete;
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private:
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static Singleton2 instan;
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};
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Singleton2 Singleton2::instan;
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