Implement enum in c# Interface and in one of interface's method signature

Question

I have an interface

Interface:

interface IThing
{
  Enum MyEnum {get;set;}
  string DoAction(MyEnum enumOptionChosen, string valueToPassIn);
}

Concrete implementation:

public class Thing : IThing
{
  public enum MyEnum
  {
    FirstOption,
    SecondOption,
    ThirdOption
  }

  string doAction(MyEnum enumOptionChosen, string valueToPassIn)
  {
    switch(enumOptionChosen)
    {
      case MyEnum.FirstOption:
        x();
        break;
      case MyEnum.SecondOption:
        y();
        break;
      case MyEnum.ThirdOption:
        z();
        break;
    }
  }
}

When I try compiling this I get 'IThing.MyEnum' is a 'property' but is used like a 'type.' I'm missing something about being able to require use of the Enum in the DoAction() signature.

Thanks for any help.

Btw, the error occurs in the Interface, not in the implementation. — 0bytes
– 0bytes, Commented Oct 19, 2010 at 3:38

bendewey · Accepted Answer · 2010-10-19 04:05:30Z

17

In your interface MyEnum is the name of the variable not the type, so it won't be recognized by the compiler. You should be able to use Generics to get this done.

public interface IThing<T>
{
   T MyEnum { get; set; }
   string doAction(T enumOptionChosen, string valueToPassIn);
}

Then you could implement it like this:

public interface IThing<T>
{
    T MyEnum { get; set; }
    string doAction(T enumOptionChosen, string valueToPassIn);
}

public class Something : IThing<Something.SpecialEnum>
{
    public enum SpecialEnum
    {
        Item1,
        Item2,
        Item3
    }

    public SpecialEnum MyEnum { get; set; }

    public string doAction(SpecialEnum enumOptionChosen, string valueToPassIn)
    {
        return "something";
    }
}

edited Oct 19, 2010 at 4:05

answered Oct 19, 2010 at 3:45

bendewey

40.4k13 gold badges105 silver badges126 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Code Jammr Over a year ago

T will have to be used whenever using the Interface though.

c-chavez Over a year ago

To enforce T as an Enum, you can use IThing<T> where T : Enum

RPM1984 · Accepted Answer · 2010-10-19 03:42:05Z

3

Firstly, declare your enum outside of the interface/concrete.

Then in your interface:

MyEnum SomeNum {get; set;}

Then in your class:

public MyEnum SomeNum 
{
   get
   {
     ...
   }
   set
   {
      ...
   }
}

Your main problem was you were trying to declare a return type of "Enum" from your interface, when you should be declaring a return type of "MyEnum".

Remember, enum is a type. You can't force a class to implement a "type", only properties/methods.

That being said, i'm scratching my head to try and figure out what you are trying to do.

answered Oct 19, 2010 at 3:42

RPM1984

73.3k62 gold badges241 silver badges364 bronze badges

Comments

Jack Whipnert · Accepted Answer · 2018-06-14 18:21:06Z

1

I realize the original post is very old, but this is another approach that is clear and works well. Since the Enum is public, just go ahead and define it outside of the concrete class and the interface. (I've taken the liberty of renaming the enum type to TheEnum to avoid confusion with the property MyEnum.)

public enum TheEnum
{
    FirstOption,
    SecondOption,
    ThirdOption
}

Then reference it in your interface and concrete class.

public interface IThing
{
    TheEnum MyEnum { get; set; }
    string DoAction(TheEnum enumOptionChosen, string valueToPassIn);
}

public class Thing : IThing
{
    public TheEnum MyEnum { get; set; }

    public string DoAction(TheEnum enumOptionChosen, string valueToPassIn)
    {
        return "Something";
    }
}

answered Jun 14, 2018 at 18:21

Jack Whipnert

2952 silver badges9 bronze badges

1 Comment

Aaron Hudon Over a year ago

That's fine, except when IThing and TheEnum are from different assemblies you may not be able to pull this off.

Collectives™ on Stack Overflow

Implement enum in c# Interface and in one of interface's method signature

3 Answers 3

2 Comments

Comments

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

2 Comments

Comments

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related