C# と VB.NET の質問掲示板

■No2761 (まきこ さん) に返信
> イメージとしては下記のような処理をしたいと思っています。
> if (this.comboBox1.SelectedIndexChanged == null) {}

一応、こんな感じで判定できましたが……実用性は無いかも。


private void button1_Click(object sender, EventArgs e)
{
    Delegate[] methodList = GetCaller(comboBox1);
    StringBuilder sb = new StringBuilder("comboBox1 の SelectedIndexChanged イベントは未登録");
    if (methodList.Length > 0)
    {
        sb = new StringBuilder();
        foreach (Delegate method in methodList)
        {
            sb.AppendLine(method.Method.Name);
        }
    }
    MessageBox.Show(sb.ToString());
}

public Delegate[] GetCaller(ComboBox target)
{
    Type type = typeof(ComboBox);

    BindingFlags all = BindingFlags.Default;
    all |= BindingFlags.Public;
    all |= BindingFlags.NonPublic;
    all |= BindingFlags.Instance;
    all |= BindingFlags.IgnoreCase;
    all |= BindingFlags.Static;

    EventDescriptorCollection events = TypeDescriptor.GetEvents(target);
    EventDescriptor myEvent = events.Find("SelectedIndexChanged", false);
    MethodInfo mi = type.GetMethod("get_Events", all);
    EventHandlerList list = (EventHandlerList)mi.Invoke(target, new object[] { });
    FieldInfo fi = type.GetField("EVENT_SELECTEDINDEXCHANGED", all);
    object key = fi.GetValue(target);
    if (list[key] == null)
    {
        return new Delegate[0];
    }
    else
    {
        return list[key].GetInvocationList();
    }
}