C＃：返回给定对象的委托和方法名 [英] C#: Return a delegate given an object and a method name

问题描述

假如我是给定一个对象，并保存的方法名称的字符串，我怎么可以返回一个委托给该方法（该方法的？）？

Suppose I'm given an object and a string that holds a method name, how can I return a delegate to that method (of that method?) ?

例如：

MyDelegate GetByName(ISomeObject obj, string methodName)
{
    ...
    return new MyDelegate(...);
}

ISomeObject someObject = ...;
MyDelegate myDelegate = GetByName(someObject, "ToString");

//myDelegate would be someObject.ToString

先谢谢了。

Thanks in advance.

一件事 - 我真的不希望使用switch语句，即使它会工作，但一吨的代码

One more thing -- I really don't want to use a switch statement even though it would work but be a ton of code.

推荐答案

您需要使用的 Type.GetMethod 得到正确的方法，和的 Delegate.CreateDelegate 转换的的MethodInfo 成代表。完整的例子：

You'll need to use Type.GetMethod to get the right method, and Delegate.CreateDelegate to convert the MethodInfo into a delegate. Full example:

using System;
using System.Reflection;

delegate string MyDelegate();

public class Dummy
{
    public override string ToString()
    {
        return "Hi there";
    }
}

public class Test
{
    static MyDelegate GetByName(object target, string methodName)
    {
        MethodInfo method = target.GetType()
            .GetMethod(methodName, 
                       BindingFlags.Public 
                       | BindingFlags.Instance 
                       | BindingFlags.FlattenHierarchy);

        // Insert appropriate check for method == null here

        return (MyDelegate) Delegate.CreateDelegate
            (typeof(MyDelegate), target, method);
    }

    static void Main()
    {
        Dummy dummy = new Dummy();
        MyDelegate del = GetByName(dummy, "ToString");

        Console.WriteLine(del());
    }
}

迈赫达德的评论是一个伟大的，虽然 - 如果异常这个过载抛出 Delegate.CreateDelegate 都还好，可以简化 GetByName方法显著：

Mehrdad's comment is a great one though - if the exceptions thrown by this overload of Delegate.CreateDelegate are okay, you can simplify GetByName significantly:

    static MyDelegate GetByName(object target, string methodName)
    {
        return (MyDelegate) Delegate.CreateDelegate
            (typeof(MyDelegate), target, methodName);
    }

我从来没有使用这个我自己，因为我通常做检查的其他位）

I've never used this myself, because I normally do other bits of checking after finding the MethodInfo explicitly - but where it's suitable, this is really handy :)

这篇关于C＃：返回给定对象的委托和方法名的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！