Xtykutl

I have

struct MyType

{

   public int value;

}

How can I define an explicit operator so that it is castable to any enum ? "any" means any enum in existence.

The "convertible to any possible enum" function is already possible if it is an int and not a struct containing int. For example I can always (AnyEnum)myType.value, (SomeOtherEnum)myType.value. But I would like to be able to do (AnyEnum)myType directly without digging an int inside. My idea is naturally, utilizing implicit in some way which will treat the whole thing as int. But unfortunately implicit does not support generic, so I would have to define implicit for every enum I wish to support.

It is fine if this involves some use of C# 7.3's Enum generic constraint. But it seems even with the constraint where T : Enum I cannot cast an int to T by (T)value. ("Cannot convert type int to T)

An example use case :

if(myValue.something == something)

{

   switch((MyEnum)myValue)

   {

       case MyEnum.A : ...

       case MyEnum.B : ...

   }

}

else if(myValue.something == something)

{

   switch((MyOtherEnum)myValue)

   {

       case MyOtherEnum.A : ...

       case MyOtherEnum.B : ...

   }

}

Another one,

if(myValue.ValidInEnum<MyEnum>(out MyEnum validEnum)) //converted from inside with some additional logic

{

   switch(validEnum)

   {

       case MyEnum.A : ...

       case MyEnum.B : ...

   }

}

If you want to convert from an enum directly instead of having to access the "value" member of your struct, yes, it is possible, here is an example:

static void Main(string args)

{

    MyType myType;

    myType.value = 1;

    MyEnum myEnum = (MyEnum) myType;

    Console.WriteLine(myEnum);

    Console.ReadLine();

}



enum MyEnum

{

    a = 0,

    b = 1

}



struct MyType

{

    public int value;



    public static explicit operator MyEnum(MyType myType)

    {

        return (MyEnum)myType.value;

    }

}

The output is:

b

If you want to cast from any type of enum directly to your struct, I don't think that would be possible, you can look into generics as suggested in the other answer, or maybe write a little extension helper for your type:

public static class MyTypeExtensions

{

    public static T ToAnyEnum<T>(this MyType myType)

    {

        return (T)Enum.ToObject(typeof(T), myType.value);

    }

}

Then you can write:

MyType myType;

myType.value = 1;

MyEnum myEnum = myType.ToAnyEnum<MyEnum>();

MyOtherEnum myOtherEnum = myType.ToAnyEnum<MyOtherEnum>();

It's not possible. You cannot create a cast operator for any enum type, only for concrete enum types I'm afraid you would have go through the "big hassle" of doing:

var anyEnum = (AnyEnum)myType.value;

Another way would be using something like a ToEnum method maybe:

struct MyType

{

    int value;



    public T ToEnum<T>() where T : struct

    {

        return (T)Enum.ToObject(typeof(T), this.value);

    }

}

Usage:

var anyEnum = myType.ToEnum<AnyEnum>();

You could also create an explicit cast to your value type:

public static explicit operator int(MyType myType)

{

    return myType.value;

}

Then you can do:

var anyEnum = (AnyEnum)(int)myType;

I admit it's not really much shorter, but this would allow to make value private for example or do any other custom logic in the conversion.

Personal Note

I don't believe this kind of design makes much sense. It just tries to answer the original question. It was interesting to think about it.