Delegates and Event

Hi all

I am trying to use a code sniplet from a source, but the error CS0079 was prompted, saying that StatusMessageChange should only appear on the left side of += or -+. Can someone kindly help me.

Code:

---

namespace IBIX
{
        public class BatchInfo
        {
                public delegate void StatusMessageChangeHandle(object tmp, StatusMessageChangeEventArgs e);


                public event BatchInfo.StatusMessageChangeHandle StatusMessageChange
                {
                        add
                        {
                                this.StatusMessageChange = (BatchInfo.StatusMessageChangeHandle)Delegate.Combine(this.StatusMessageChange, value);
                        }
                        remove
                        {
                                this.StatusMessageChange = (BatchInfo.StatusMessageChangeHandle)Delegate.Remove(this.StatusMessageChange, value);
                        }
                }

}
}

---

Much appreciated.

sounds like (but I did not tested) you're looking for:

Code:

---

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

namespace DelegateCombineCSharp
{
    public class BatchInfo
    {
        public delegate void StatusMessageChangeHandle(object tmp, StatusMessageChangeEventArgs e);

        private  BatchInfo.StatusMessageChangeHandle _StatusMessageChange;
        public event BatchInfo.StatusMessageChangeHandle StatusMessageChange
        {
            add
            {
                this._StatusMessageChange += (BatchInfo.StatusMessageChangeHandle)Delegate.Combine(this._StatusMessageChange, value);
            }
            remove
            {
                this._StatusMessageChange -= (BatchInfo.StatusMessageChangeHandle)Delegate.Remove(this._StatusMessageChange, value);
            }
        }

    }
   
}

---

wait: it should be as follows:

Code:

---

public class BatchInfo
    {
        public delegate void StatusMessageChangeHandle(object tmp, StatusMessageChangeEventArgs e);

        private  BatchInfo.StatusMessageChangeHandle _StatusMessageChange;
        public event BatchInfo.StatusMessageChangeHandle StatusMessageChange
        {
            add
            {
                this._StatusMessageChange = (BatchInfo.StatusMessageChangeHandle)Delegate.Combine(this._StatusMessageChange, value);
            }
            remove
            {
                this._StatusMessageChange = (BatchInfo.StatusMessageChangeHandle)Delegate.Remove(this._StatusMessageChange, value);
            }
        }

    }

---

Code:

---

namespace WindowsFormsApplication1
{
  public partial class Form1 : Form
  {
      private BatchInfo info;
      /// <summary>
      /// Constructzor
      /// </summary>
      public Form1()
      {
          InitializeComponent();
          info = new BatchInfo(); // BatchInfo class is crreated here
          // delegate is added here
          info.StatusMessageChange += new BatchInfo.StatusMessageChangeHandle(info_StatusMessageChange);
      }
      /// <summary>
      /// Using the event outside the class
      /// </summary>
      /// <param name="tmp"></param>
      /// <param name="e"></param>
      void info_StatusMessageChange(object tmp, EventArgs e)
      {
          /// Your code is here
      }
 
  }
  public class BatchInfo
  {
      public delegate void StatusMessageChangeHandle(object tmp, EventArgs e);
      private event StatusMessageChangeHandle statusChange;
      public BatchInfo() {
          this.StatusMessageChange += new StatusMessageChangeHandle(BatchInfo_StatusMessageChange);
      }
      /// <summary>
      /// A delegate used within the class itself
      /// </summary>
      /// <param name="tmp"></param>
      /// <param name="e"></param>
      void BatchInfo_StatusMessageChange(object tmp, EventArgs e)
      {
          // Your code is here
      }
 
      /// <summary>
      /// Here is the event explicitly typed
      /// </summary>
      public event StatusMessageChangeHandle StatusMessageChange
      {
          add
          {
              this.statusChange  += value;
              // you adfdress the private event or you will get Stackoverflow
              // because of redirecting to the same name!!!
          }
          remove
          {
              this.statusChange -= value;
          }
      }
  }
}

---

Hope this helps a bit- Shows how to use a delegate inside a class and outsid a class

Thanks everyone. This forum has been very helpful to me. Awesome beautiful people here.

In this scenario you could simply write:


public event BatchInfo.StatusMessageChangeHandle StatusMessageChange;

This will implicitly have the normal "add" and "remove" handlers. I'm just mentioning this in case you thought you had to write the add/remove handlers similar to how a property requires you write get/set methods.