Implement events through interface in C#

April 7, 2008 · 5 min read

According to C# specification interface contain a signature of events but a complete and brief implementation of events through interface is not available on the net.

First you identify the interface

    public interface IControl
    {
        // Raise this event.
        event EventHandler OnCommand;
    }

According to my need I create a class that inherit from System.EventArgs

    public class CommandArgs : EventArgs
    {
        public string CommandName;
    }

My OutCommand class is a implementation of IControl interface that contain an OnCommand event.

public class OutCommnad : IControl
    {
        public OutCommnad()
        {}
 
        // Create an event from interface event
        event EventHandler CommandEvent;
        event EventHandler IControl.OnCommand
        {
            add
            {
                if (CommandEvent != null)
                {
                    lock (CommandEvent)
                    {
                        CommandEvent += value;
                    }
                }
                else
                {
                    CommandEvent = new EventHandler(value);
                }
            }
            remove
            {
                if (CommandEvent != null)
                {
                    lock (CommandEvent)
                    {
                        CommandEvent -= value;
                    }
                }
            }
        }
 
        public void Command()
        {
            EventHandler handler = CommandEvent;
            if (handler != null)
            {
                //My custom class that passed as arguments.
                CommandArgs cmd = new CommandArgs();
                cmd.CommandName = "Test Application event.";
                handler(this, cmd);
            }
        }
    }

Calling of IControl.OnCommand event.

    OutCommnad outCommand = new OutCommnad();
    IControl con = (IControl)outCommand;
    con.OnCommand +=new EventHandler(con_OnCommand);
    outCommand.Command();

IControl.OnCommand event function.

        void con_OnCommand(object sender, CommandArgs e)
        {
            string str = e.CommandName;
            Console.WriteLine(str);
        }
This article is part of the GWB Archives. Original Author: Saqib Ullah

New on Geeks with Blogs

  • We Won The One Award I Actually Care About

    Full Scale made the Inc. 5000 for the fifth year straight, the 12th listing across my three companies. Here is why the one award you cannot buy is worth stopping for.

  • Your Customers Build the Features Now

    I let a tool I liked sit dead for a year rather than build the features I wanted. An MCP server meant I never had to, and your customers can do the same to your product.

  • Get the Size of a Directory in Linux the Easy Way

    du -sh for the quick answer, ncdu for the cleanup, df for the disk itself: every command for checking directory size in Linux, plus why du and df never agree.

  • Vim Search and Replace: The Ultimate Guide

    One :%s command replaces every match in a file before a find dialog would even open. The Vim substitute patterns worth the muscle memory: flags, ranges, capture groups, and multi-file edits.