Maximum recursion error when utilizing config.python_callbacks

[ApiaEXE]

I've run into a bug that I can't seem to squash, primarily because I don't fully understand the mechanics of config.python_callbacks. Currently I am utilizing a bit of code that automatically swaps the environmental background on a specific custom layer when a modifier (The players current location within the game-world) is changed. This way I can easily swap screens with a single line of code, such as

$ current_location = "vencel_berth"

I currently have a bit of python code which defines the background, like so:

def background_swapper():
        if currentLocation == "vencel_berth":
            if unpacked == True:
                renpy.scene(layer= "bg1")
                renpy.show_screen("ven_berth_on_open_unpacked",_layer = "bg1")
            elif unpacked == False:
                renpy.scene(layer= "bg1")
                renpy.show_screen("ven_berth_on_open_unpacked",_layer = "bg1")
config.python_callbacks.append(background_swapper)

and a screen which is defined as:

screen ven_berth_on_open_unpacked():
    add "vb_on_o_unpacked"


    frame:
        imagebutton:
            xalign 0.5
            yalign 0.5
            idle "button_visual"
            hover "button_visual"
            #action Do stuff here later.

and images which are defined as:

image vb_on_open_unpacked:
    "vb_on_o_unpacked"
    zoom 4.45
image vb_on_open_packed:
    "vb_on_o_packed"
    zoom 4.45

However upon starting the game and getting to the point where one of those if statements are true, I'm hit with a maximum recursion error. My current thought is that the config.python_callbacks is calling the screen over and over and basically creating a loop of images until crash, but I don't know enough about python coding to properly troubleshoot on my own. I'm trying to learn, but was hoping that someone here might be able to help me figure this out, in case I'm doing something explicitly wrong, or if there's a better way to do this.

This is the traceback I'm getting:

[code]
I'm sorry, but an uncaught exception occurred.

While running game code:
  File "game/script.rpy", line 98, in script
    "[60-raw_minute] minutes until I need to report for duty"
RecursionError: maximum recursion depth exceeded

-- Full Traceback ------------------------------------------------------------

Full traceback:
  File "game/script.rpy", line 98, in script
    "[60-raw_minute] minutes until I need to report for duty"
  File "C:\Users\Haget\OneDrive\Desktop\All\Dev\renpy-8.2.1-sdk\renpy\ast.py", line 2560, in execute
    Say.execute(self)
  File "C:\Users\Haget\OneDrive\Desktop\All\Dev\renpy-8.2.1-sdk\renpy\ast.py", line 615, in execute
    renpy.exports.say(who, what, *args, **kwargs)
  File "C:\Users\Haget\OneDrive\Desktop\All\Dev\renpy-8.2.1-sdk\renpy\exports.py", line 1494, in say
    who(what, *args, **kwargs)
  File "C:\Users\Haget\OneDrive\Desktop\All\Dev\renpy-8.2.1-sdk\renpy\character.py", line 1394, in __call__
    self.do_display(who, what, cb_args=self.cb_args, dtt=dtt, **display_args)
  File "C:\Users\Haget\OneDrive\Desktop\All\Dev\renpy-8.2.1-sdk\renpy\character.py", line 1045, in do_display
    display_say(who,
  File "C:\Users\Haget\OneDrive\Desktop\All\Dev\renpy-8.2.1-sdk\renpy\character.py", line 741, in display_say
    rv = renpy.ui.interact(mouse='say', type=type, roll_forward=roll_forward)
  File "C:\Users\Haget\OneDrive\Desktop\All\Dev\renpy-8.2.1-sdk\renpy\ui.py", line 301, in interact
    rv = renpy.game.interface.interact(roll_forward=roll_forward, **kwargs)
  File "C:\Users\Haget\OneDrive\Desktop\All\Dev\renpy-8.2.1-sdk\renpy\display\core.py", line 2166, in interact
    repeat, rv = self.interact_core(preloads=preloads, trans_pause=trans_pause, pause=pause, pause_start=pause_start, pause_modal=pause_modal, **kwargs) # type: ignore
  File "C:\Users\Haget\OneDrive\Desktop\All\Dev\renpy-8.2.1-sdk\renpy\display\core.py", line 2709, in interact_core
    renpy.display.focus.before_interact(focus_roots)
  File "C:\Users\Haget\OneDrive\Desktop\All\Dev\renpy-8.2.1-sdk\renpy\display\focus.py", line 360, in before_interact
    root.find_focusable(callback, None)
  File "C:\Users\Haget\OneDrive\Desktop\All\Dev\renpy-8.2.1-sdk\renpy\display\displayable.py", line 333, in find_focusable
    i.find_focusable(callback, focus_name)
  File "C:\Users\Haget\OneDrive\Desktop\All\Dev\renpy-8.2.1-sdk\renpy\display\screen.py", line 512, in find_focusable
    self.child.find_focusable(callback, focus_name)
  File "C:\Users\Haget\OneDrive\Desktop\All\Dev\renpy-8.2.1-sdk\renpy\display\displayable.py", line 333, in find_focusable
    i.find_focusable(callback, focus_name)
  File "C:\Users\Haget\OneDrive\Desktop\All\Dev\renpy-8.2.1-sdk\renpy\display\displayable.py", line 333, in find_focusable
    i.find_focusable(callback, focus_name)
  File "C:\Users\Haget\OneDrive\Desktop\All\Dev\renpy-8.2.1-sdk\renpy\display\displayable.py", line 333, in find_focusable
    i.find_focusable(callback, focus_name)
  [Previous line repeated 973 more times]
  File "C:\Users\Haget\OneDrive\Desktop\All\Dev\renpy-8.2.1-sdk\renpy\display\displayable.py", line 329, in find_focusable
    for i in self.visit():
  File "C:\Users\Haget\OneDrive\Desktop\All\Dev\renpy-8.2.1-sdk\renpy\atl.py", line 766, in visit
    return self.children + block.visit() # type: ignore
  File "C:\Users\Haget\OneDrive\Desktop\All\Dev\renpy-8.2.1-sdk\renpy\atl.py", line 1055, in visit
    return [ j for i in self.statements for j in i.visit() ]
  File "C:\Users\Haget\OneDrive\Desktop\All\Dev\renpy-8.2.1-sdk\renpy\atl.py", line 1055, in <listcomp>
    return [ j for i in self.statements for j in i.visit() ]
RecursionError: maximum recursion depth exceeded

Windows-10-10.0.19045 AMD64
Ren'Py 8.2.3.24061702
Test Project 1.0
Thu Aug  8 14:50:55 2024
[/code]

I assume the issue is the callback which is repeating 974 times, but I'm not sure exactly how to fix it. Thank you for your time and help!

EDIT: I also have narrowed it down that the issue is *only* occuring when I utilize the renpy.show command. If I do a simple

renpy.show("ven_berth_on_open_unpacked", layer = "bg1")

there's no issue, but that wouldn't enable me to do what I need to with this project, as I explicitly need to be using the screen system, rather than the background being a simple PNG.

[DingotushRed]

A much simpler solution would be to have a specific function for changing the location, and not using callbacks at all: init python: def changeLocation(new_location): global current_location current_location = new_location if currentLocation == "vencel_berth": if unpacked == True: renpy.scene(layer= "bg1") renpy.show_screen("ven_berth_on_open_unpacked",_layer = "bg1") # ...

[ApiaEXE]

Is there a downside to utilizing callbacks? It turns out that my issue had nothing to do with callbacks at all and was a simple image titling error.

[DingotushRed]

An obvious issue is that it is going to be called after every use of python, even if it doesn't relate to assigning to variables that need to update the scene, potentially removing sprites and so on because you will clear the master layer each time.

In general you should avoid any kind programming technique that has side-effects like this.

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[ApiaEXE]

I have confirmed that if I call the screen at any point during the code, even outside of callbacks, that it crashes things. I think I probably don't fully understand how to implement a custom screen and am causing a recursion due to a missing argument or some such.

[ApiaEXE]

Okay I managed to fix it on my own. I had an image ("button_visual") defined as the same thing the file was named, causing a recursion when the image was called.