c#泛型和反射的設計應用

From 心靈魔術師s blog
在設備操作面板的設計中總會有一類固定的按鈕和操作慣例，但如果每做一個項目都寫一套同樣的代碼實在很沒效率的事。

    設備的操作按鈕大多數都會包含啟動、暫停、停止這三個按鈕，軟件界面中也同樣需要這三類按鈕，軟件需要根據設備的狀態

來禁用或啟用不同的按鈕組合。比如剛啟動軟件時，啟動按鈕開啟，暫停和停止按鈕禁用等等。

    一般設計情況下是用Button,也有的設計會用ToolStripButton，為了使其兼容更多的控件，所以采用了泛型。代碼如下：

   
    public enum OperateState { Run, Pause, Stop };

    public class OperateStateRule<T> where T : ToolStripItem
    {
        private T start;
        private T pause;
        private T stop;

        private OperateState state = OperateState.Stop;

        private OperateState State
        {
            get { return state; }
            //set { state = value; }
        }

        public OperateStateRule(T _start, T _pause, T _stop)
        {
            start = _start;
            pause = _pause;
            stop = _stop;

            Update(OperateState.Stop);
        }

        public void Update(OperateState _state)
        {
            state = _state;
            try
            {
                switch (state)
                {
                    case OperateState.Stop:
                        start.Enabled = true;
                        pause.Enabled = false;
                        stop.Enabled = false;
                        break;
                    case OperateState.Run:
                        start.Enabled = false;
                        pause.Enabled = true;
                        stop.Enabled = true;
                        break;
                    case OperateState.Pause:
                        start.Enabled = true;
                        pause.Enabled = false;
                        stop.Enabled = true);
                        break;
                }
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
        }
    }

    調用示例：

     ToolStripButton btnStart；
     ToolStripButton btnPause；
     ToolStripButton btnStop；

     //生成對象時綁定相應的按鈕
     OperateStateRule<ToolStripButton> rule = new  OperateStateRule<ToolStripButton>(btnStart,btnPause,btnStop);
     //在Click事件裡更新狀態
      private void btnStart_Click(object sender, EventArgs e)
        {
            rule.Update(OperateState.Run);
        }

        private void btnPause_Click(object sender, EventArgs e)
        {
            rule.Update(OperateState.Pause);
        }

        private void btnStop_Click(object sender, EventArgs e)
        {
            rule.Update(OperateState.Stop);
        }
    

    在類聲明上有個where T : ToolStripItem語句，這個是c#類型約束，如果不加這個約束，編譯器會報錯找不到Enabled屬性，

但有個問題Button和ToolStripButton這兩個類不是同一個基類派生，所以無法兼容使用這2個類，因為必須要有這個約束，使得c++

的一些泛型做法受到限制。

    那還有沒有更好的方法來達到理想的效果呢，答案是有的，就是反射。看下面改進的代碼例子：

    public enum OperateState { Run, Pause, Stop };

    public class OperateStateRule<T>
    {
        private T start;
        private T pause;
        private T stop;

        private OperateState state = OperateState.Stop;

        private OperateState State
        {
            get { return state; }
            //set {