Question

我有一个扩展UserControl的控件。此控件包含两个ComboBox控件。我创建了一个事件处理程序，当其中一个组合发生变化时会触发：


public event EventHandler ComboChanged
{
add { cmbA.SelectedIndexChanged += value; cmbB.SelectedIndexChanged += value; }
remove {...}
}

当我向此事件添加事件处理程序时，是否有任何方法可以将sender报告为自定义控件（即ComboBox的父控件）而不是ComboBox本身？或者我想做一些我不应该做的事情？

Answer 1

你应该有这样的东西：

public event EventHandler MyControlChanged

然后在你的userControl中为每个ComboBox提供两个函数

protected void oncmbA_SelectedIndexChanged(object sender, EventArgs e)
{
   if (MyControlChanged!=null)
     MyControlChanged(this, e);//or some new Eventagrs that you wish to communicate
}

protected void oncmbB_SelectedIndexChanged(object sender, EventArgs e)
{
   if (MyControlChanged!=null)
     MyControlChanged(this, e);//or some new Eventagrs that you wish to communicate
}

然后会引用UserControl而不是引发UserControl事件的组合框。

Answer 2

Yoann的答案是要走的路。这是一个类似的模式，但有一些细微的差别。

// Default listener makes null-check unnecessary when raising event.
// Note that no custom implementations are provided for add, remove.
public event EventHandler ComboChanged = delegate { };

...

foreach(var comboxBox in new[] {cmbA, cmbA})
{
  // Attach listener to combo-box's event that raises our own event.
  // Lambda-expression is ok since we don't intend to ever unsubscribe.
  comboBox.SelectedIndexChanged += (sender, args) => ComboChanged(this, args);
}

自定义控件的事件发件人

2 个答案: