如何在哈希表中存储方法？

Question

我试图在C#中的哈希表中存储方法列表,这样我就可以在用户输入所需的密钥时立即执行该方法.我想知道我会怎么做.我被告知我可以使用匿名接口或代理来执行此操作.哪个更好？为什么？我没有找到太多关于这实际上会如何实现的参考.

例:

key =方法

"+"= object.add

" - "= object.minus

Answer 1

这是一个过度简化的解决方案,但它说明了完成您的要求所需的步骤.

public class Test
{
    // Ok, we declare the hashtable here. It could be a Dictionary though, so we don't have to
    // cast it. But you requested a hashtable.
    private Hashtable hash = new Hashtable();

    // Were it a dictionary, we'd have:
    // private Dictionary<string, Calculation> dict = new Dictionary<string, Calculation>();

    // We declare the signature of the methods that we will store. This means that we accept any
    // methods which receive two decimal parameters and return a decimal output
    private delegate decimal Calculation(decimal x, decimal y);

    public Test()
    {
    }

    public void Run()
    {
        // A sample implementation of the delegate
        Calculation sum = (decimal x, decimal y) =>
        {
            return x + y;
        };

        // Another sample implementation
        Calculation minus = (decimal x, decimal y) =>
        {
            return x - y;
        };

        // Here we add both of them to the hashtable
        this.hash.Add("+", sum);
        this.hash.Add("-", minus);

        // Were it a dictionary, we'd have:
        // this.dict.Add("+", sum);
        // this.dict.Add("+", minus);

        // Note that in the hashtable you can put ANYTHING. Were it a dictionary, it would be strong-typed and
        // we'd be able to only add Calculation types

        // Now ask the user for input values
        Console.Write("X: ");
        var xInput = decimal.Parse(Console.ReadLine());

        Console.Write("Y: ");
        var yInput = decimal.Parse(Console.ReadLine());

        // Ask the user which method to execute
        Console.WriteLine("Which method to execute? Enter number:");
        Console.WriteLine("1. +");
        Console.WriteLine("2. -");
        Console.Write("> ");

        var choice = int.Parse(Console.ReadLine());

        // Get the selected method from the hashtable
        Calculation calc;
        if (choice == 1)
        {
            calc = (Calculation)this.hash["+"];
        }
        else if (choice == 2)
        {
            calc = (Calculation)this.hash["-"];
        }
        else
        {
            throw new ArgumentOutOfRangeException();
        }

        // Were it a dictionary, we'd have (note that we don't have to cast it):
        // calc = this.dict["-"];

        // execute it, and output the result
        Console.WriteLine("Result: " + calc(xInput, yInput));

        Console.ReadKey();
    }
}