How to convert any int into any generic Enum in C#?-CodePudding

Because Enums aren't guaranteed to be of type int...

public enum ExampleEnum : int / ulong / whatever

You cannot do this with enums:

int i = (int)exampleEnum;

However in my case, while I don't know the exact 'type of enum' being used, I can guarantee that it will be a "int type" of enum.

So I can do this:

int i = Convert.ToInt32(exampleEnum);

Cool. Here's the problem: I don't know of a way to do the inverse (which I need to do), as:

Enum exampleEnum = (Enum)exampleEnum;

has error:

Cannot cast expression of type 'int' to type 'Enum'

And I cannot find an inverse of Convert.ToInt32(Enum enum)

That is the question, if you think more detail on what I'm trying to do is useful, I can provide you with it. But in a nutshell I am creating a generic GUI method that takes in any type of Enum:

public static int EditorPrefEnumField(string label, Enum defaultValue, string editorPrefString)

and getting it to work (the way I want) involves converting the Enum to and from an int.

CodePudding user response：

You can use Enum.ToObject() method. You need to specify the actual enum type for that. Here is a generic method to encapsulate Enum.ToObject()

public enum TestEnum : int 
{
    A=1, B=2, C=3
};

public T GetEnumFromInt<T>(int value) where T : Enum
{
    return (T)Enum.ToObject(typeof(T), value);
}

private void button1_Click(object sender, EventArgs e) 
{
    Enum value = GetEnumFromInt<TestEnum>(2);
    MessageBox.Show(value.ToString()); // Displays "B" 
}

You need to specify the concrete type of Enum you want because Enum is an abstract type and one cannot create instances of abstract types.

CodePudding user response：

Take this code where I store an error code as an Int:

public class CommonError
{
   public int Code { get; set; }

   public CommonError FromErrorCode(Enum code, string description = "")
   {
        Code = (int)Enum.Parse(code.GetType(), code.ToString());                        
        return this;
   }
}

Yet what I'm doing when I call it is parsing in different Enums:

new CommonError().FromErrorCode((int)GeneralErrorCodes.SYSTEM_BASE_ERROR);

Cool. Here's the problem: I don't know of a way to do the inverse (which I need to do)

To do the reverse of this you need the Enum Type, eg:

Enum.GetNames(typeof(AnEmumType))

Enum.GetValues(typeof(AnEmumType)).ToList();