[Feature Suggestion] Enum inheritance

[Krzysztof Zoławy]

Hi,

I'd like to share with my idea to new lombok feature - enum inheritance.

As we now, in Java we cannot extends enums. In some cases this functionality would be very useful. Consider example:

With Lombok:

enum Position {

  TOP,

  BOTTOM,

  LEFT,

  RIGHT

}

@ExtendsEnum(Position.class)

enum ExtendedPosition {

  TOP_LEFT_CORNER,

  TOP_RIGHT_CORNER, 

  BOTTOM_LEFT_CORNER,

  BOTTOM_RIGHT_CORNER

}

Vanilla Java:

enum Position {

  TOP,

  BOTTOM,

  LEFT,

  RIGHT

}

enum ExtendedPosition {

  TOP,

  BOTTOM,

  LEFT,

  RIGHT,

  TOP_LEFT_CORNER,

  TOP_RIGHT_CORNER, 

  BOTTOM_LEFT_CORNER,

  BOTTOM_RIGHT_CORNER

}

[Jan Materne]

I dont think that its that useful. Your extended enum could only used in your own code  On the other gand you would just copy a few lines..

Jan

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[Mat Jaggard]

Agreed. You'd also expect to be about to pass the extended enum into something that accepts the base enum like with object inheritance but that wouldn't work with this kind of fake inheritance - which is exactly why Java doesn't allow enums to inherit each other in the first place.

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[Floris Kraak]

If you really want to inherit some things (methods, obviously, since the values aren't really inheritable) - enums can implement interfaces which can implement default methods. 

So you could have both of those enums implement something like, say, a PositionalThingMabob interface and make the rest of the code not care about what position is involved exactly or where it's coming from that way.

Obviously Lombok doesn't need to be involved for that though.

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