单件

来源：互联网发布：智诚轮胎软件编辑：程序博客网时间：2024/06/10 01:08

#include<iostream>using namespace std;class Singleton{static Singleton s;int i;Singleton( int x):i(x) {  }Singleton& operator=(Singleton&); Singleton(const Singleton&);public:static Singleton& instance() { return s; }int getValue(){ return i;}void setValue(int x){ i=x; }}; Singleton Singleton::s(50);int main(){Singleton& s=Singleton::instance();cout<<s.getValue()<<endl;Singleton& s2=Singleton::instance();s2.setValue(9);cout<<s.getValue()<<endl;}#include<iostream>using namespace std;class Singleton{int i;Singleton(int x):i(x){ }void operator=(Singleton&);Singleton(const Singleton&);public:static Singleton& instance(){static Singleton s(47);return s;}int getValue(){ return i;}void setValue(int x) { i=x;}}; int main(){Singleton& s=Singleton::instance();cout<<s.getValue()<<endl;Singleton& s2=Singleton::instance();s2.setValue(9);cout<<s.getValue()<<endl; }//如果两个单件彼此依赖，就会产生一个特别有趣的情况 class Singleton1{Singleton1(){}public:static Singleton1& ref(){static Singleton1 single;return single;}};class Singleton2{Singleton1& s1;Singleton2(Singleton1& s):s1(s){}public:static Singleton2& ref(){static Singleton2 single(Singleton1::ref());return single;}Singleton1& f(){return s1;}};int main(){Singleton1& s1=Singleton2::ref().f();}#include<iostream>using namespace std;template<class T> class Singleton{Singleton(const Singleton&);Singleton& operator=(const Singleton&);protected:Singleton(){}virtual ~Singleton(){}public:static T& instance(){static T theInstance;return theInstance;}}; class MyClass:public Singleton<MyClass>{int x;protected:friend class Singleton<MyClass>;MyClass() { x=0;}public:void setValue(int n) { x=n;}int getValue() const { return x;}};int main(){MyClass& m=MyClass::instance();cout<<m.getValue()<<endl;m.setValue(1);cout<<m.getValue()<<endl;

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