具有通用类型的方法，设置值

Question

I have a method which is something like below and i want to set the value of it with input string.

How would i go about it? Any advice will be greatly appreciated

private static void QueueCheckNAdd<T>(ref T param, string input)
    {
        param.DoSomethingLikeSetValue(input);
    }

for your reference, the generic type is something like int or double

Answer 1

param = (T)(object)Convert.ChangeType(input, typeof(T));

必须进行强制转换才能使编译器确信结果确实是T类型。

Answer 2

You want param to be generic (ie, any type), and you expect to be able to call some method on it, correct? Well, you can see the problem there: if param can be any type, there's no way to guarantee that it will have the method DoSomethingLikeSetValue (or whatever). I'm sure you could get fancy with introspection or runtime type coercion, but I think the "clean" way to do what you're looking for is to constrain the type of T to some interface that has the required method ( DoSomethingLikeSetValue ). Like this:

private static void QueueCheckNAdd<T>(ref T param, string input) where T : IHasSomething {
    param.DoSomethingLikeSetValue(input);
}

public interface IHasSomething {
    void DoSomethingLikeSetValue(string s);
}

Then you can invoke QueueCheckNAdd generically only if the generic type supports the IHasSomething interface. So you could use it like this:

public class Foo : IHasSomething {
    public void DoSomethingLikeSetValue(string s) {
        Console.WriteLine(s);
    }
}

var f = new Foo();
QueueCheckNAdd<Foo>(f, "hello");

Answer 3

Good practice would be to use interface like described before,

But if you want some fun, you could aslo use the object as a dynamic object, like below:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApplication1
{
    class SMTHG
    {
        public void DoSomethingLikeSetValue(string input)
        {
            Console.WriteLine("HEYYYYY!!! DYNAMIC OBJECTS FTW!...\n" + input);
        }
    }
    class Program
    {
        private static void QueueCheckNAdd<T>(ref T param, string input)
        {
            dynamic dynamicObject = (dynamic)param; 
            dynamicObject.DoSomethingLikeSetValue(input);
        }
        static void Main(string[] args)
        {
            SMTHG smthg = new SMTHG();
            QueueCheckNAdd(ref smthg, "yoyuyoyo");
        }
    }
}