Declarative Children

If a Go structs extends a Node-derived class, any exported Node-derived fields will be populated automatically. This means graphics.gd will look for any children that match the same name as the field (or the name within the gd struct tag) and either populate the field with the first child found or create a new instance of the field’s type if no child is found.

This is useful for ensuring that any nodes that your struct depends on to be located in the scene tree are present. The gd struct tag can either be a name, a path, or a uniquely-named node, ie %MyNode.

package main

import (
  "fmt"

  "graphics.gd/classdb"
  "graphics.gd/classdb/Control"
  "graphics.gd/classdb/Button"
  "graphics.gd/classdb/Label"
  "graphics.gd/startup"
)

type MyGUI struct {
  Control.Extension[MyNode]

  Label struct {
    Label.Instance `gd:"Label"` // will point to the "Label" child

    ClickMe Button.Instance `gd:"ClickMe"` // will point to a "ClickMe" child
  }
}

func (m *MyGUI) Ready() {
  m.Label.SetText("My GUI")
  m.Label.ClickMe.AsBaseButton().OnPressed(func() {
    fmt.Println("Button clicked!")
  })
}

func main() {
  classdb.Register[MyGUI]()
  startup.LoadingScene()
  SceneTree.Add(new(MyGUI))
  startup.Scene()
}