using System;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Tres".ToEnum<Teste>(defaultValue: "Dois"));

    }

}

​

public enum Teste

{

    Un = 1,

    Dois = 2

}

​

public static class StringExtensions

{

    public static bool IsEmpty(this string? str)

    {

        return string.IsNullOrWhiteSpace(str);

    }

    public static T ToEnum<T>(this string value, string defaultValue = null) where T : struct

    {

        if (value.IsEmpty() && defaultValue.IsEmpty())

        {

            return default(T);

        }

​

        return Enum.TryParse(value.GetValueOrDefault(defaultValue), true, out T result) ? result : default(T);

    }

​

    public static string? GetValueOrDefault(this string? str, string? defaultValue)

    {

        return str.IsNotNullOrEmpty() ? str : defaultValue;

    }

​

    public static string? GetValueOrDefault(this string? str, Func<string?> defaultValue)

    {

        return str.IsNotEmpty() ? str : defaultValue();

    }

​

    public static bool IsNotEmpty(this string str)

    {

        return !string.IsNullOrWhiteSpace(str);

    }

​

    public static bool IsNotNullOrEmpty(this object obj) =>

        obj is not null && obj.ToString().IsNotEmpty();

}