using System;

using System.Collections.Generic;

​

public class Program

{

    private static readonly Dictionary<Type, Func<Exception, string>> exceptionMappings = new Dictionary<Type, Func<Exception, string>>();

​

    public static void Map<TException>(Func<TException, string> mapToError) where TException : Exception

    {

        // Cambiar esta linea usando cast

        exceptionMappings.Add(typeof(TException), x => mapToError((TException)x));

​

        // Por algo que no requiera cast

        // Argument 2: cannot convert from 'System.Func<TException,string>' to 'System.Func<System.Exception,string>'

        exceptionMappings.Add(typeof(TException), mapToError);

    }

​

    public static void Main()

    {

        Map<InvalidOperationException>(x => "Prefix: " + x.Message);

        var invalidEx = new InvalidOperationException("My exception message");

        var errorMessage = exceptionMappings[invalidEx.GetType()](invalidEx);

        Console.WriteLine(errorMessage);

    }

}