Question

我的班级中有一个私人物品。如果该对象触发一个事件，我想将事件传递给使用我的类的任何东西。目前我这样做，我把我的构造函数：

cbName.CheckedChanged += ((sender, args) => this.CheckChanged(this,args));

有没有更好的方法来做到这一点，是否有任何像类不会被处置的问题，因为它有自己的事件，我需要在dispose函数中手动取消订阅？

将发件人从触发对象更改为this是可选的。

完整版测试代码

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Drawing;
using System.Data;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace placeholder
{
    internal class FilterBase : UserControl, IFilterObject
    {
        public FilterBase(string name)
        {
            InitializeComponent();
            cbName.CheckedChanged += ((sender, args) => this.CheckChanged(this,args));
            cbName.Name = name;
            this.Name = name;
        }

        private CheckBox cbName;
        /// <summary> 
        /// Required designer variable.
        /// </summary>
        private System.ComponentModel.IContainer components = null;

        /// <summary> 
        /// Clean up any resources being used.
        /// </summary>
        /// <param name="disposing">true if managed resources should be disposed; otherwise, false.</param>
        protected override void Dispose(bool disposing)
        {
            if (disposing && (components != null))
            {
                components.Dispose();
            }
            base.Dispose(disposing);
        }

        #region Component Designer generated code

        /// <summary> 
        /// Required method for Designer support - do not modify 
        /// the contents of this method with the code editor.
        /// </summary>
        private void InitializeComponent()
        {
            this.cbName = new System.Windows.Forms.CheckBox();
            this.SuspendLayout();
            // 
            // cbName
            // 
            this.cbName.AutoSize = true;
            this.cbName.Location = new System.Drawing.Point(4, 4);
            this.cbName.Name = "cbName";
            this.cbName.Size = new System.Drawing.Size(79, 17);
            this.cbName.TabIndex = 0;
            this.cbName.Text = "Filter Name";
            this.cbName.UseVisualStyleBackColor = true;
            // 
            // UserControl1
            // 
            this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F);
            this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
            this.AutoSize = true;
            this.AutoSizeMode = System.Windows.Forms.AutoSizeMode.GrowAndShrink;
            this.Controls.Add(this.cbName);
            this.Name = "Filter Name";
            this.Size = new System.Drawing.Size(86, 24);
            this.ResumeLayout(false);
            this.PerformLayout();

        }

        #endregion

        public event EventHandler CheckChanged;
        public bool Checked
        {
            get { return cbName.Checked; }
        }
    }
}

Answer 1

event实际上类似于自动属性。您可以定义自己的add和remove方法，将委托直接传递给子控件，从而删除额外的间接级别：

public event EventHandler CheckChanged {
    add { cbName.CheckChanged += value; }
    remove { cbName.CheckChanged -= value; }
}

这将删除存储在您班级中的额外Delegate（因为Delegate字段用于标准事件的幕后花絮）

Answer 2

那么，这会阻止当前对象在cbName处于活着状态时被垃圾收集，但听起来这不太可能是一个问题...而且它是固有的，因为你有一个参考到this无论你做什么（因为你想要激活这个对象的 CheckChanged处理程序）。

这样做的一个缺点是，即使您愿意也不能取消订阅（例如在Dispose方法中）。另一种方法是使用实际方法：

private void CbNameCheckedChangedHandler(object sender, EventArgs e)
{
    CheckedChanged(this, args);
}

...
cbName.CheckedChanged += CbNameCheckedChangedHandler;

// If you ever want to remove the handler
cbName.CheckedChanged -= CbNameCheckedChangedHandler;

请注意，这是假设您的CheckedChanged事件为空安全，例如它被声明为：

public event EventHandler CheckedChanged = delegate {};

否则，如果没有人订阅该活动，则会在NullReferenceException触发时获得cbName.CheckedChanged。

事件发生事件

2 个答案: