How to make a Godot-style singleton

[FranChauntry]

Hi there,

Is Singleton possible as it is in vanilla Godot? Is there a Nimonic way of doing this? I'm a bit new to it so I'm not sure if there's a proper way.

What I'm doing at the moment is create a Global type in a file called global.nim and I simply "import global" whenever I want to use it in other files. It doesn't feel like a global object I can access anytime though.

[panno8M]

Your method is best for use with Nim only. That is, the following pattern

# globals.nim
type Global* = object
  value*: int
var global*: Global

import gdext
import gdext/classes/gdNode
import globals

type Main* {.gdsync.} = ptr object of Node

method ready (self: Main) {.gdsync.} =
  global.value = 10

If you want to refer to it from GDScript as well, you need to devise a way to do so using the Godot mechanism.

# globals.nim
import gdext
import gdext/classes/gdEngine

type Global* {.gdsync.} = ptr object of Object
  value* {.gdexport.}: int

var global*: Global

proc register_Global_singleton {.execon: initialize_scene.} =
  # This callback is called from initialize_scene by the execon macro.
  # initialize_scene is an event to register the new class with the engine when this extension is loaded.
  global = instantiate Global
  Engine.singleton.registerSingleton("Global", global)

proc free_Global_singleton {.execon: eliminate_scene.} =
  Engine.singleton.unregisterSingleton("Global")
  destroy global

import gdext
import gdext/classes/gdNode
import globals

type Main* {.gdsync.} = ptr object of Node

method ready (self: Main) {.gdsync.} =
  global.value = 10

class_name Main
extends Node

func _ready():
  Global.value = 10

[FranChauntry]

Thanks!