c# - 如何传递方法名称以实例化委托(delegate)？

Question

在下面的示例中，我想定义一个 System.Action，它执行我在运行时定义的特定方法，但是我如何传递方法名称(或方法本身)，以便Action 方法可以定义委托(delegate)以指向该特定方法吗？

我目前遇到以下错误:

“methodName”是一个“变量”，但像“方法”一样使用

using System;
using System.Collections.Generic;

namespace TestDelegate
{
    class Program
    {
        private delegate void WriteHandler(string message);

        static void Main(string[] args)
        {
            List<string> words = new List<string>() { "one", "two", "three", "four", "five" };
            Action<string> theFunction = WriteMessage("WriteBasic");

            foreach (string word in words)
            {
                theFunction(word);
            }
            Console.ReadLine();
        }

        public static void WriteBasic(string message)
        {
            Console.WriteLine(message);
        }

        public static void WriteAdvanced(string message)
        {
            Console.WriteLine("*** {0} ***", message);
        }

        public static Action<string> WriteMessage(string methodName)
        {
            //gets error: 'methodName' is a 'variable' but is used like a 'method'
            WriteHandler writeIt = new WriteHandler(methodName);

            return new Action<string>(writeIt);
        }

    }
}

Answer 1

您不需要委托(delegate)声明或 WriteMessage 方法。尝试以下操作:

using System;
using System.Collections.Generic;

namespace TestDelegate
{
    class Program
    {
        static void Main(string[] args)
        {
            List<string> words = new List<string>() { "one", "two", "three", "four", "five" };
            Action<string> theFunction = WriteBasic;

            foreach (string word in words)
            {
                theFunction(word);
            }
            Console.ReadLine();
        }

        public static void WriteBasic(string message)
        {
            Console.WriteLine(message);
        }

        public static void WriteAdvanced(string message)
        {
            Console.WriteLine("*** {0} ***", message);
        }

    }
}

Action 已经是一个委托(delegate)，所以你不需要再做一个。