Godot 4 Pinned Notes

These notes are to either handle Godot 4’s language changes, or to correct wrong knowledge.

Godot 4.2 language changes

• Scene unique variables.
  Variables can be set unique in a scene to refer to Godot controls. This is done by using the % sign. So, if I make a any control in the editor and set the unique name property, I can then access that node by prefixing % to the name in GDScript. Example:
  – set it: a VBoxControl unique name to %fubar in the editor.
  – use it: %fubar.add_child(checkbox)
• .connect API change.
  The node.connect API has changed. Previously, the 3 argument API was .connect(signal_name, object, handler_name) where both signal_name and handler_name were strings representing the signal to subscribe to and the handler, respectively. Now, the API has 2 arguments, the signal_name, and the function in the object instance to call. Example:
  old: http_request.connect(“request_completed”, self, “_on_request_completed”)
  new: http_request.connect(“request_completed”, self._on_request_completed)
• parse_json is deprecated. Use the JSON class instead. Example:
  var my_json = JSON.new()
  var foo = my_json.parse_string{json_string)
• Reference base class renamed to RefCounted
• rect_min_size control property is deprecated.

GDScript Error Corrections:

• Signals expose a connect function with parameter binding to the receiver. Here’s an example with checkbox:
  # Create a checkbox, connect the pressed signal to a receiver, and send a parameter to the receiver instance
  var receiver_object = Receiver.new()
  var send_parameter = 1
  var checkbox = CheckBox.new()
  checkbox.pressed.connect(reciever_object.function.bind(send_parameter))
• Callbacks must be of type Callable, and called via .call.
  Other call syntax is incorrect. If I want to bind a single function callback, I have to do it like this:
  func use_callback(callback: Callable):
  var my_param = 1
  var output = callback.call(my_param)