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模板代码

#pragma once
#include <mutex>
#include <atomic>// CRTP基类模板 Curiously Recurring Template Parttern—奇异递归模板模式。
template <typename T>
class SingletonCRTP {
public:// 禁止拷贝构造和赋值操作SingletonCRTP(const SingletonCRTP&) = delete;SingletonCRTP& operator=(const SingletonCRTP&) = delete;// 禁止移动构造和赋值操作SingletonCRTP(SingletonCRTP&&) = delete;SingletonCRTP& operator=(SingletonCRTP&&) = delete;// 获取单例实例static T* getInstance() {if (m_instance == nullptr) {std::unique_lock<std::mutex> lock(m_Mutex); // 加锁if (m_instance == nullptr) {T* temp = new (std::nothrow) T();if (temp == nullptr) {throw std::bad_alloc();}m_instance = temp;}}return m_instance;}protected:SingletonCRTP() = default;~SingletonCRTP() {if (m_instance) {delete m_instance;m_instance = nullptr;}}// 静态成员变量定义static T* m_instance;static std::mutex m_Mutex;
};// 静态成员变量的模板类特化
template <typename T>
T* SingletonCRTP<T>::m_instance = nullptr;template <typename T>
std::mutex SingletonCRTP<T>::m_Mutex;

使用方式

#include "SingletonCRTP.h"
class Class1 : public SingletonCRTP<Class1>
{friend class SingletonCRTP<Class1>;
public:void DoDoDo() {printf("Hello World!");}}
int main(int argc, char *argv[])
{Class1::getInstance()->DoDoDo();
}