代码之家 › 专栏 › 技术社区 › Cade Roux

如何统一/简化此代码-事件处理/委派?

delegates refactoring .net c#

Cade Roux · 技术社区 · 16 年前

    private void ctxgrphAddBreakpoint_Click(object sender, EventArgs e)
    {
        Process p = GetProcess(viewer);
        if (p != null)
        {
            p.AddBreakpoint();
            BeginRefresh(false, false);
        }
    }

    private void ctxgrphRemoveBreakpoint_Click(object sender, EventArgs e)
    {
        Process p = GetProcess(viewer);
        if (p != null)
        {
            p.RemoveBreakpoint();
            BeginRefresh(false, false);
        }
    }

    private void ctxlistAddBreakpoint_Click(object sender, EventArgs e)
    {
        foreach (Process p in lvwProcessList.SelectedProcesses())
        {
            p.AddBreakpoint();
        }
        BeginRefresh(false, false);
    }

    private void ctxlistRemoveBreakpoint_Click(object sender, EventArgs e)
    {
        foreach (Process p in lvwProcessList.SelectedProcesses())
        {
            p.RemoveBreakpoint();
        }
        BeginRefresh(false, false);
    }

    private void ctxlistAction_Click(object sender, EventArgs e)
    {
        // I can unify the Viewer and ListView and implement some common interface,
        // so I'm pretty sure I can handle this part
        foreach (Process p in UIView.SelectedProcesses())
        {
            p.Action(); // What is the best way to handle this?
        }
        BeginRefresh(false, false);
    }

我怎么去那里?

4 回复 | 直到 16 年前

Kelly S. French 16 年前

访客模式?

Nestor 16 年前

... += new System.EventHandler(ctxlistAction_Click); )在*。Designer.cs文件,并使它们指向相同的函数。

mdm20 16 年前

你不能把发送者直接转换到你的界面上吗?

 private void ctxlistAction_Click(object sender, EventArgs e)
 {
      UIView view = sender as UIView;

      if (view != null)
      {

         // I can unify the Viewer and ListView and implement some common interface,
         // so I'm pretty sure I can handle this part
         foreach (Process p in view.SelectedProcesses())
         {
             p.Action(); // What is the best way to handle this?
         }
         BeginRefresh(false, false);
      }
  }

dan 16 年前

(请原谅我对“DoListAction”等名称的错误选择):

readonly Action<Process> removeBreakpoint = p => p.RemoveBreakpoint();
readonly Action<Process> addBreakpoint = p => p.AddBreakpoint(); 

void DoSingleAction(Action<Process> action)
{
     var p = GetProcess(viewer);
     if(p != null)
     {
         action(p); //invokes the action
         BeginRefresh(null,null);
     }
}

void DoListAction(Action<Process> action)
{
    lvwProcessList.ForEach(action);
    BeginRefresh(false, false);
}



private void ctxgrphAddBreakpoint_Click(object sender, EventArgs e)
{
    DoSingleAction(addBreakpoint);
}

private void ctxgrphRemoveBreakpoint_Click(object sender, EventArgs e)
{
    DoSingleAction(removeBreakpoint);
}

private void ctxlistAddBreakpoint_Click(object sender, EventArgs e)
{
    DoListAction(addBreakpoint);
}

private void ctxlistRemoveBreakpoint_Click(object sender, EventArgs e)
{
    DoListAction(removeBreakpoint);
}

void DoAction(object sender, Action<Process>)
{
     if(sender is ListView)
     {
         lvwProcessList.ForEach(action);
         BeginRefresh(false, false);
     }
     else if (sender is GraphView)
     {
         var p = GetProcess(viewer);
         if(p != null)
         {
             action(p); //invokes the action
             BeginRefresh(null,null);
         }
     }
     else {throw new Exception("sender is not ListView or GraphView");}
}

//and update all the handlers to use this, and delete DoSingleAction and DoListAction:
private void ctxgrphAddBreakpoint_Click(object sender, EventArgs e)
{
    DoAction(sender, addBreakpoint);
}
//etc.

无论如何,在每个事件处理程序中,我认为你必须指定要采取的行动。我不确定在这种情况下继承或扩展方法是否真的是你的朋友,但使用扩展方法可能会是这样:

//these two are in a separate static class
public static InvokeAction(this ListView listView, Action<Process> action)
{ ... }
public static InvokeAction(this GraphView listView, Action<Process> action)
{ ... }

private void handler(object sender, Action<Process> action)
{ 
    var lv = sender as ListView;
    var gv = sender as GraphVeiw;    
    lv.InvokeAction(action); //(need to check for null first)
    gv.InvokeAction(action);
    if(lv == null && gv == null) {throw new Exception("sender is not ListView or GraphView");}
}

//then update all the handlers:
private void ctxgrphAddBreakpoint_Click(object sender, EventArgs e)
{
    handler(sender, addBreakpoint);
}

C#2/。NET 2.0

在C#2中(VS2005),使用委托的第一种方式仍然有效,只是不能使用lambdas。(2.0有 Action<T>

void removeBreakpoint(Process p) { p.RemoveBreakpoint(); }
void addBreakpoint(Process p) { p.AddBreakpoint(); }

//you could also do this, but it's overkill:
readonly Action<Process> removeBreakpoint = delegate(Process p) { p.RemoveBreakpoint(); };
readonly Action<Process> addBreakpoint = delegate(Process p) { p.AddBreakpoint(); };