using System;

using System.Linq;

using System.Reflection;

using System.Runtime.CompilerServices;

public class Program {

    class CommandHandler {

        public readonly MethodInfo method;  // method to call (assume static)

        public readonly Type[] argtypes;    // method's parameter types

        // construct for given method of given type

        public CommandHandler (Type type, string methodName) {

            method = type.GetMethod(methodName);

            argtypes = (from p in method.GetParameters() select p.ParameterType).ToArray();

        }

        // parse string arg array to appropriate types then invoke

        public void Invoke (params string[] argstrs) {

            object[] args = argstrs.Select((str, n) => Convert.ChangeType(str, argtypes[n])).ToArray();

            method.Invoke(null, args);

        }

    }

​

    // example (int, int) methods with various parameter modifiers

    public static void Handler (int a, int b) => log(a + b);

    public static void HandlerIn (in int a, in int b) => log(a + b);

    public static void HandlerRef (ref int a, ref int b) => log(a + b);

    public static void HandlerOut (out int a, out int b) => log((a=0) + (b=0));

    // -------- test code --------

    // test CommandHandler for given method in Program.

    static void Test (string methodName) {

        log(methodName);

        var ch = new CommandHandler(typeof(Program), methodName);

        log($"  {string.Join<Type>(", ", ch.argtypes)}");

        try {

            ch.Invoke("1", "2");

        } catch (Exception x) {

            log($"  {x.GetType().Name}: {x.Message}");

        }

    }

    // a quick test directly with correct types just as a sanity check

    static void CanIEvenCallThis (string methodName) {

        log(methodName);

        object[] args = { 8, 9 };

        typeof(Program).GetMethod(methodName).Invoke(null, args);

        log($"  args on return: [{string.Join(", ", args)}]");

    }

    // run test on each of the example methods

    public static void Main () {

        string[] methods = { "Handler", "HandlerIn", "HandlerRef", "HandlerOut" };

        foreach (var m in methods) Test(m);

        foreach (var m in methods) CanIEvenCallThis(m);

    }

    static void log (object what, [CallerMemberName] string from = null) =>

        Console.WriteLine($"{from}: {what}");

}

​