Structural example
#include <iostream>
using namespace std;
// The 'Subject' abstract class
class Subject {
public:
virtual void Request() = 0;
};
// The 'RealSubject' class
class RealSubject : public Subject {
public:
virtual void Request() {
cout << "Called RealSubject.Request()" << endl;
}
};
// The 'Proxy' class
class Proxy : public Subject {
private:
RealSubject *_realSubject;
public:
Proxy() {
_realSubject = NULL;
}
virtual ~Proxy() {
if (_realSubject) delete _realSubject;
}
virtual void Request() {
// Use 'lazy initialization'
if (_realSubject == NULL) {
_realSubject = new RealSubject;
}
_realSubject->Request();
}
};
// Entry point into console application.
int main() {
// Create proxy and request a service
Proxy *proxy = new Proxy;
proxy->Request();
delete proxy;
return 0;
}
Real World example
#include <iostream>
using namespace std;
// The 'Subject' interface
class IMath {
public:
virtual double Add(double x, double y) = 0;
virtual double Sub(double x, double y) = 0;
virtual double Mul(double x, double y) = 0;
virtual double Div(double x, double y) = 0;
};
// The 'RealSubject' class
class Math : public IMath {
public:
double Add(double x, double y) { return x + y; }
double Sub(double x, double y) { return x - y; }
double Mul(double x, double y) { return x * y; }
double Div(double x, double y) { return x / y; }
};
// The 'Proxy Object' class
class MathProxy : public IMath {
private:
Math *_math;
public:
MathProxy() {
_math = new Math;
}
virtual ~MathProxy() {
delete _math;
}
double Add(double x, double y) {
return _math->Add(x, y);
}
double Sub(double x, double y) {
return _math->Sub(x, y);
}
double Mul(double x, double y) {
return _math->Mul(x, y);
}
double Div(double x, double y) {
return _math->Div(x, y);
}
};
// Entry point into console application.
int main() {
// Create math proxy
MathProxy *proxy = new MathProxy;
// Do the math
cout << "4 + 2 = " << proxy->Add(4, 2) << endl;
cout << "4 - 2 = " << proxy->Sub(4, 2) << endl;
cout << "4 * 2 = " << proxy->Mul(4, 2) << endl;
cout << "4 / 2 = " << proxy->Div(4, 2) << endl;
delete proxy;
return 0;
}
参考サイト
最終更新：2011年12月21日 01:08
