Why is Godot not applying changes of global (singleton) variables instantly?

Question

Hey. I am trying to implement a jump potion into my game which changes the jump height of player from -600 to -1000. I have declared the jump height variable in a script called "globals.gd" which is an enabled singleton.
For some reason the new jump height (of -1000) ist only applied when my KinematicBody2D (the Player) has died and the current scene is reloaded but not when he collects the jump potion (Area2D with signal "body_entered").

Comments

please show the scripts.

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Sry, my bad. I cut it to the relevant parts.

The Player.gd

var JUMP_HEIGHT = Globals.JUMP_HEIGHT   # globals singleton
func _physics_process(delta):
#The jump part
    if is_on_floor():
        if Input.is_action_just_pressed("ui_up"):
            motion.y = JUMP_HEIGHT
        if friction == true:
        motion.x = lerp(motion.x, 0, 0.1)

The jump_potion.gd

func _on_Jump_Potion_body_entered(body):
    set_process(true)
    if body.name == "Player":
        Globals.JUMP_HEIGHT = -1000
        $Timer.start()
        print("AREA ENTERED")
        queue_free()
    else:
        pass


func _on_Timer_timeout():
    Globals.JUMP_HEIGHT = -600

The globals.gd (singleton)

var JUMP_HEIGHT = -600

Answer 1

Code is VERY relevant ;)

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Cause:
You create a variable JUMPHEIGHT and set it in the frist line to the value of Globals.JUMPHEIGHT. But after that, you never update JUMPHEIGHT.
JUMPHEIGHT is just a variable, not a reference. So it does not change, when you change Globals.JUMP_HEIGHT.

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Solution(s):

• always use Globals.JUMPHEIGHT instead of JUMPHEIGHT
• update JUMPHEIGHT on every _physicsprocess before calculations

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PS.: You should not use UPPERCASE-Variable names. Thats for constants and enums ;)
Of course it works, but can cause confusion if you show your code to others.
(See here)

Comments

Thanks. By directly using the global variable, everything works fine. I thought that by changing the reference variable the referenced variable itself will change too.
I guess that's some pretty stupid beginner mistake xD.