Delegates and Event

[tomteo99]

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.

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.

[Cimperiali]

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

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);
            }
        }

    }
    
}

[Cimperiali]

wait: it should be as follows:

 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);
            }
        }

    }

[JonnyPoet]

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

[tomteo99]

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

[Mutant_Fruit]

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.