使用代理类限制隐式转换

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#include<iostream>using namespace std;//ImplictChange只有一个数据成员xclass ImplictChange{public:    ImplictChange(int a) : x(a) {}   //explicit可以防止隐式转换    friend bool operator==(const ImplictChange& rhs,const ImplictChange& lhs) {return(rhs.x == lhs.x);}private:int x;};//用代理类来限制隐式转换//原理:隐式转换只能被调用一次class NoImplictChange{public:    //增加代理类class Proxy{public:Proxy(int a) : x(a) {}int getX() const{return(x);}private:int x;};     NoImplictChange(const Proxy& p) : pro(p) {}      friend bool operator==(const NoImplictChange& rhs,const NoImplictChange& lhs) { return(rhs.pro.getX() == lhs.pro.getX()); }private:    Proxy pro;};int main(){     ImplictChange a(1); if(1 == a)              //此处就出现了隐式转换 { cout << 1 << endl; }     NoImplictChange b(1); if(1 == b) { cout << 1 << endl; } return(0);}