c# - 在一种方法中添加和删除事件，c#

Question

有时我需要在一堆控件中添加和删除事件。我总是使用一种添加事件的方法来做到这一点:

private void AddEvents(){
    textBox.TextChanged += TextChanged;
    integerUpDown.ValueChanged += ValueChanged;
    colorPicker.SelectedColorChanged += ColorChanged;
    //... and so on
}

同样的一个用于删除事件:

private void RemoveEvents(){
    textBox.TextChanged -= TextChanged;
    integerUpDown.ValueChanged -= ValueChanged;
    colorPicker.SelectedColorChanged -= ColorChanged;
    //... and so on
}

我正在使用不同类型的控件和不同类型的 EventArgs。我想将其压缩为一种方法，例如:

private void RemoveEvents(bool add){
    textBox.TextChanged add ? += : -= TextChanged;
    integerUpDown.ValueChanged add ? += : -= ValueChanged;
    //or method approach
    ManageEvent(colorPicker.SelectedColorChanged, ColorChanged, add);
    //... and so on
}

但这不可能吗？运算符(operator)。有办法吗？

Answer 1

我认为这很好。

首先，定义如下接口(interface)和类:

public interface IEventHolder
{
    void Attach();
    void Detach();
}

public class EventHolder<H> : IEventHolder
{
    private Action<H> _add;
    private Action<H> _remove;
    private H _handler;

    public EventHolder(Action<H> add, Action<H> remove, H handler)
    {
        _add = add;
        _remove = remove;
        _handler = handler;
    }

    public void Attach() { _add(_handler); }

    public void Detach() { _remove(_handler); }
}

现在您可以定义这个私有(private)字段:

    private List<IEventHolder> _eventHolders = new List<IEventHolder>();

在 Form_Load 事件中我写了这段代码:

    private void Form1_Load(object sender, EventArgs e)
    {
        _eventHolders.Add(new EventHolder<EventHandler>(h => textBox1.TextChanged += h, h => textBox1.TextChanged -= h, textBox1_TextChanged));
        _eventHolders.Add(new EventHolder<EventHandler>(h => numericUpDown1.ValueChanged += h, h => numericUpDown1.ValueChanged -= h, numericUpDown1_ValueChanged));
        _eventHolders.Add(new EventHolder<MouseEventHandler>(h => textBox2.MouseMove += h, h => textBox2.MouseMove -= h, textBox2_MouseMove));

        _eventHolders.ForEach(eh => eh.Attach());
    }

请注意 _eventHolders.ForEach(eh => eh.Attach()); 行附加了所有事件。

我的处理程序看起来像这样:

    private void textBox1_TextChanged(object sender, EventArgs e)
    { }

    private void numericUpDown1_ValueChanged(object sender, EventArgs e)
    {
        this.textBox1.Text = numericUpDown1.Value.ToString();
    }

    private void textBox2_MouseMove(object sender, MouseEventArgs e)
    {
        _eventHolders.ForEach(eh => eh.Detach());
    }

textBox2_MouseMove 处理程序一次性分离所有事件。

我已经测试过了，效果很好。