My goal would be to build a plugin to make certain classes observable while making them simpler to d...

# compiler

[Federico Tomassetti]

My goal would be to build a plugin to make certain classes observable while making them simpler to define.

so I would transform a class like this:

data class A(p1: Int) : Node()

into

class A(p1: Int) : ObservableNode() {

  init {
      println("initializing p1 at $p1") // instead of print we will notify observers
  }
  var p1 : Int = p1
    get() {
      print("reading p1") // instead of print we will notify observers
      return field
    }
    set(value: Int) {
      println("setting p1 to $value (currently at $field)") // instead of print we will notify observers
      field = value
    }

  override fun equals(other: Any?): Boolean {
    if (this === other) return true
    if (other !is A) return false

    return p1 == other.p1
  }

  override fun hashCode(): Int {
    return p1
  }
}

I can find the ClassDeclaration and check if it extends Node, but it is unclear to me how to modify it. I tried removing the irClass in the declarations of IrFile and replace it with a copy but that cause errors

[Javier]

would p1 be available to the consumer so they can reference it? if so, maybe it should be done with the frontend?

[Federico Tomassetti]

p1 should be available both in the original code and in the modified code, so that code using the A class would not really need to change. However I would like to change its definition by adding the getter and setter (where I would sneak in methods to notify observers)

[Federico Tomassetti]

To do that in the frontend, should I use a different extension?

[Javier]

For frontend yes

[Javier]

if you modify it on backend you couldn't see that green on the IDE I think, as val number: Int = a.p1 , that p1 wouldn't exist for the IDE as it will exist later.

[Federico Tomassetti]

sorry, I realize I was missing a val in the original data class which would be:

data class A(val p1: Int) : Node()

So I think the val p1 would be present also in the original code (even if with a different definition)

[Tóth István Zoltán]

To do that transformation you would want to replace the initializer of the variable. That is an IrExpression which you could transform into another IrExpression that contains the prints. You can use an IrElementTransformerVoidWithContext for that and the visitAnonymousInitializerNew and visitPropertyNew functions in particular.

I added an example below that is a transformer. It shows how a transformation is done and actually contains calls to printf in a form of trace functions. It is in-development and is a somewhat broken at the moment but you can see examples there.

https://github.com/spxbhuhb/rui/blob/7468ca0db6d345298247e80367883f53f0158e8a/rui-[…]/simplexion/rui/kotlin/plugin/ir/air2ir/StateAccessTransform.kt

[Oliver.O]

Could you please avoid copying messages to the channel and keep channel posts short? Especially long code excerpts and stack traces make it hard for readers on mobile devices to skip postings there.

[ftomassetti]

Ok, I removed it. Thank you for providing feedback. Is there another place where one should ask for help regarding the compiler plugin?

[Javier]

you can comment here, he was referring to avoid long code outside the thread

[ftomassetti]

ok, so I can post code or stack traces but only within a thread, correct?

[Oliver.O]

Just do short posts in the channel for new topics, then answer in the respective thread. Just do not tick the box „also send to channel „.

[ftomassetti]

Understood, I will do that in the future. Thank you