技術(shù)原理:

1. 私有化構(gòu)造函數(shù)席镀，析構(gòu)函數(shù)卧檐，拷貝構(gòu)造函數(shù)和賦值操作符切蟋，不讓外部構(gòu)造秸妥，并將默認函數(shù)實現(xiàn)設置為delete
2. 使用std::shared_ptr管理單例內(nèi)存滚停，避免內(nèi)存泄漏
3. 使用可變參數(shù)模板構(gòu)造任意對象

代碼如下
singleton.hpp

#ifndef _SINGLETON_HPP_
#define _SINGLETON_HPP_
#include <memory>

template <typename T>
using shared_ptr = typename std::shared_ptr<T>;

template <typename T> 
class Singleton {
    public:
        template <typename ... Args> 
        static shared_ptr<T>&  Instance(Args&& ... args) {
            if(!m_pInstance) {
                m_pInstance = shared_ptr<T>(new T(std::forward<Args>(args)...));
            }
            return m_pInstance;
        }

    private:
        static shared_ptr<T> m_pInstance;
        Singleton() = delete;
        virtual ~Singleton() = delete;
        Singleton(const Singleton&) = delete;
        Singleton& operator=(const Singleton&) = delete;
};

template <typename T>
shared_ptr<T> Singleton<T>::m_pInstance = nullptr;

#endif

main.cpp

#include "singleton.hpp"
#include <iostream>
using std::cout;
using std::endl;

struct Person
{
    Person(): m_Name("呵呵"), m_Age(20) {

    }

    Person(std::string name, int age): m_Name(name), m_Age(age) {}

    std::string m_Name;
    int m_Age;
};

struct Visitor {
    Visitor(): m_Name("呵呵"), m_Age(20) {

    }
    std::string m_Name;
    int m_Age;
};

int main(void) {
    shared_ptr<int> sInt = Singleton<int>::Instance(100);
    cout << *sInt << endl;

    // 兩次調(diào)用都獲得 張三
    cout << "Person類相關(guān)信息輸出: " << endl;
    shared_ptr<Person> p = Singleton<Person>::Instance("張三", 30);
    cout << "姓名: " << p->m_Name << " 年齡: " << p->m_Age << endl;
    shared_ptr<Person> p2 = Singleton<Person>::Instance();
    cout << "姓名: " << p2->m_Name << " 年齡: " << p2->m_Age << endl;

    // 調(diào)用無參構(gòu)造函數(shù)
    cout << "Visitor類相關(guān)信息輸出: " << endl;
    shared_ptr<Visitor> v = Singleton<Visitor>::Instance();
    cout << "姓名: " << v->m_Name << " 年齡: " << v->m_Age << endl;
}

Makefile

TAR=main
WORKSPACE_DIR=.
CC:=g++

.PHONY: build clear all

build:
    $(CC) -std=c++11 $(WORKSPACE_DIR)/*.*pp -g -o $(TAR)

all: clear build

clear:
    rm -rf $(TAR)

程序輸出如下

圖片.png