Proxy (proxy mode - structural mode)

Direct and indirect
People often have a way to deal with complex software systems, which is to add a layer of indirection, so as to obtain a more flexible solution to the system that meets specific needs.

Agent Mode
Motivation

Intent

Structure

Code
Version1

//version1
   //由于集中控制需求，放在集中公司总部机器上
   class Employee
   {
    
    
      public void GetSalary()
      {
    
    
      }

      public void Report()
      {
    
    
      }

      public void ApplyVacation()
      {
    
    
      }
   }
//可能应用于各个地区机器上
   class HrSystem
   {
    
    
      public void Process()
      {
    
    
         //此时这样不可用，这样使用原则是Employee类一定与HrSystem在同一地址空间
         Employee employee = new Employee();
         employee.Report();
         //...
         employee.ApplyVacation();
         //...
      }
   }

Solve
Version2

//version2
    //由于集中控制需求，放在集中公司总部机器上
    interface  IEmployee
    {
    
    
        void GetSalary();

        void Report();

        void ApplyVacation();
    }
    
    //运行在Internet远端一台机器上
    class Employee:IEmployee
    {
    
    
        public void GetSalary()
        {
    
    
        }

        public void Report()
        {
    
    
        }

        public void ApplyVacation()
        {
    
    
        }
    }

 //EmployeeProxy和HrSystem是运行在同一个地址空间
    //运行在本地Windows Form
    class EmployeeProxy : IEmployee
    {
    
    
        public EmployeeProxy()//构造器
        {
    
    
            //对对象创建的一种SOAP封装
        }

        public void GetSalary()
        {
    
    
            //对访问对象的一种SOPA封装
            //发送SOAP数据，到远程机器上。（监听来调用Employee）
            //如果有返回值，接收返回值SOAP，解包，返回原生（RAW）的C#数据
        }

        public void Report()
        {
    
    
            //...
        }

        public void ApplyVacation()
        {
    
    
            //...
        }
    }    
//可能应用于各个地区机器上
    class HrSystem
    {
    
    
        public void Process()
        {
    
    
            IEmployee employee = new EmployeeProxy();
            
            employee.Report();
            employee.ApplyVacation();
        }
    }

Key points

C# does not support operator overloading, use the interface to use the proxy
Copy-on-Write to achieve
1. Most string implementation methods

string s1 = "hello";
string s2 = "hello";
//ToUpper()  转化为大写字母
//s1.ToUpper();//不能改变S1

s1=s1.ToUpper();//这样才可以改变s1

2. Copy-on-Write implementation

StringBuilder sb1 = new StringBuilder("hello");
StringBuilder sb2 = new StringBuilder("hello");

sb1.Replace("l", "b");//sb1改变，将sb1中l改为b

Note: When there is only one StringBuilder, it is no longer copied and directly modified in place.
When the string is not prone to modification, using String Builder is more memory-intensive than using String.