using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
 
namespace DynamicCheckForFactory
{
    interface ISomething
    {
    }
 
    static class SomethingChecker
    {
        public static Func<T> CheckAndGetBuider<T>() where T : ISomething
        {
            var type = typeof(T);
            var builder = type.GetMethod("GetInstance",
                        System.Reflection.BindingFlags.Public | System.Reflection.BindingFlags.Static);
            if (builder == null)
                throw new Exception();
            return () => (T)builder.Invoke(null, null);
        }
    }
 
    class GoodSomething : ISomething
    {
        static public GoodSomething GetInstance()
        {
            return new GoodSomething();
        }
    }
 
    class BadSomething : ISomething
    {
    }
 
    class Program
    {
        static void Main(string[] args)
        {
            try
            {
                var goodBuilder = SomethingChecker.CheckAndGetBuider<GoodSomething>();
                var goodInstance = goodBuilder();
                Console.WriteLine("good instance obtained");
            }
            catch
            {
                Console.WriteLine("cannot obtain good instance");
            }
 
            try
            {
                var badBuilder = SomethingChecker.CheckAndGetBuider<BadSomething>();
                var badInstance = badBuilder();
                Console.WriteLine("bad instance obtained");
            }
            catch
            {
                Console.WriteLine("cannot obtain bad instance");
            }
        }
    }
}
 

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