C#委托防止事件多次注冊

示例代碼如下：

class  NodeInf
{
        public delegate void mydelegate(ProcessContent processContent);
        private   mydelegate myevent;

        public event mydelegate mydelegateEvent
        {
            add 
            {
                if (myevent == null)
                {
                    myevent  +=value;
                }
            }

            remove
            {
                myevent -= value;
            }
        
        }

      private void button1_Click(object sender, EventArgs e)
      {
          
            if (myevent != null && Edit==false)
            {
                ProcessContent content = new ProcessTable.ProcessContent();
                myevent(content);
            }

      }


    

}



class B
{

         void addNode(ProcessContent Content)
        {
              //dosomething

        }
        
       private void button2_Click(object sender, EventArgs e)
      {
                NodeInf nodeinf = new NodeInf(pContent);
                nodeinf.mydelegateEvent += new NodeInf.mydelegate(addNode);

      }



}