在Gosu中使用枚举代替切换用例

Question

I want to avoid creating a switch case and instead use an enum but when writing the following code, I get a compile error saying unexpected token public :

public enum Status {
  INACTIVE {
    public void doSomething() {
      //do something
    }
  },
  ACTIVE {
    public void doSomething() {
      //do something else
    }
  },
  UNKNOWN {
    public void doSomething() {
      //do something totally different
    }
  };

  public abstract void doSomething()
}

Basically what I want to achieve is something similar to this:

public enum Status {
   ACTIVE,
   INACTIVE,
   UNKNOWN;
}

switch (getState()) {
  case INACTIVE:
    //do something
    break;
  case ACTIVE:
    //do something else
    break;
  case UNKNOWN:
    //do something totally different
    break;
}

Is this allowed in Gosu? How should I go about achieving such a behavior?

Answer 1

You have miss-understood the concept of Enum . First of all, enum is inherited from java.lang.Enum . It's not allowed to implement inner classes to Enum constants . You have to consider ACTIVE,INACTIVE and UNKNOWN ( Enum constants ) as objects of class type Status.
Proof:
Status.ACTIVE.getClass() == class Status
Status.ACTIVE instanceof Status == true
Status.ACTIVE instanceof java.lang.Enum == true

If you want to avoid the switch statement in your main code, you can move the switch into the implementation of enum as follows; (coded in Gosu)

enum Status {
  ACTIVE,INACTIVE,UNKNOWN;

  public function doSomething(){
    switch (this) {
      case INACTIVE:
         //do something
         break;
      case ACTIVE:
        //do something
        break;
      case UNKNOWN:
        //do something
        break;
    }
  }
}

Now you have the capability to call the doSomething() method from the enum constants in your main code
Example:

var a=Status.ACTIVE
var b=Status.INACTIVE
var c=Status.UNKNOWN
a.doSomething()
b.doSomething()
c.doSomething()

Answer 2

As you can read in Gosu grammar or below function is not allowed inside enum consts, even brackets {} after consts are not allowed.

What is allowed in enum body:

enumBody = "{" [enumConstants] classMembers "}" .
enumConstants = enumConstant {"," enumConstant} [","] [";"] .
enumConstant = {annotation} id optionalArguments .

So basically in GOSU enum contains consts and rest normally as in any other class.