c# - 如何在分层模型中引用实例 - 当前上下文中不存在该名称

Question

我正在开发 3 层的解决方案:

• 用户界面(Winform)
• 存储(类库)
• 业务层(类库)

UI 引用业务，业务引用存储。

业务层包含一个“ Controller ”类，它将驱动各层之间的交互。

Controller 类从 UI 中的 main() 启动。 Controller 依次从业务类启动一个实例

但是启动的对象在 Controller 类中不可用。认为我们做错了什么？

/* UI: Program.cs */ 
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using System.Windows.Forms;
using Business;

namespace UI
{
    static class Program
    {
        /// <summary>
        /// The main entry point for the application.
        /// </summary>
        [STAThread]
        static void Main()
        {
            Business.Controller instController = new Business.Controller(); 

            Application.EnableVisualStyles();
            Application.SetCompatibleTextRenderingDefault(false);
            Application.Run(new UI());
        }
    }

商业.cs:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Storage;

namespace Business
{
    public class Business
    {

        private int myVar;

        public int MyProperty
        {
            get { return myVar; }
            set { myVar = value; }
        }


    }
}

Controller .CS

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Business
{
    public class Controller
    {
        Business instBusiness = new Business();

        /* line below fails, the instBusiness is not recognized) */

        instBusiness

    }
}

Answer 1

你不能在没有方法的情况下在类中执行任意代码:

public class Controller
{

    // Fields, properties, methods and events go here...

    // note, this only works because its initializing a field 
    // its the same as initializing in a constructor
    Business instBusiness = new Business();
  
    // nope, not going to work
    // instBusiness

    public Controller()
    { 
       // yay!
       instBusiness.MyProperty = 5
    }

    public void SomeOtherMethod()
    { 
       // yayer!
       instBusiness.MyProperty = 5
    }
}

---

Methods (C# Programming Guide)

A method is a code block that contains a series of statements. Aprogram causes the statements to be executed by calling the method andspecifying any required method arguments. In C#, every executedinstruction is performed in the context of a method. The Main methodis the entry point for every C# application and it is called by thecommon language runtime (CLR) when the program is started.