(Jul-24-2023, 02:10 PM)deanhystad Wrote: @snippsat is correct. You do not get the error when importing the library. It only has an effect when the program exits, which happens immediately if your program consists solely of "import vpython". Try this:

import vpython
import time

time.sleep(10)

No error until 10 seconds has passed.

My guess is the divide by zero function is a default exit function that you are meant to override.

Error:
D:\pythonProject\OpenCVLearning\venv\Scripts\python.exe D:\pythonProject\vpython\main.py 
Exception ignored in atexit callback: <function Exit at 0x0000027DBAADB420>
Traceback (most recent call last):
  File "D:\pythonProject\OpenCVLearning\venv\Lib\site-packages\vpython\vpython.py", line 22, in Exit
    a = 1.0/zero
        ~~~^~~~~
ZeroDivisionError: float division by zero
exit

Process finished with exit code 0

import atexit
import vpython
atexit.unregister(vpython.Exit)

(Jul-25-2023, 08:28 AM)Gribouillis Wrote: You could also try this

import atexit
import vpython
atexit.unregister(vpython.Exit)

import vpython
import atexit

def unregister_by_name(name):
    funs = []

    class Capture:
        def __eq__(self, other):
            funs.append(other)
            return False

    c = Capture()
    atexit.unregister(c)
    for func in funs:
        if func.__name__ == name:
            atexit.unregister(func)

unregister_by_name("Exit")

(Jul-25-2023, 08:28 AM)Gribouillis Wrote: You could also try this

import atexit
import vpython
atexit.unregister(vpython.Exit)

Error:
D:\pythonProject\OpenCVLearning\venv\Scripts\python.exe D:\pythonProject\vpython\main.py 
Traceback (most recent call last):
  File "D:\pythonProject\vpython\main.py", line 3, in <module>
    atexit.unregister(vpython.Exit)
                      ^^^^^^^^^^^^
AttributeError: module 'vpython' has no attribute 'Exit'
exit
Exception ignored in atexit callback: <function Exit at 0x0000026DC110B420>
Traceback (most recent call last):
  File "D:\pythonProject\OpenCVLearning\venv\Lib\site-packages\vpython\vpython.py", line 22, in Exit
    a = 1.0/zero
        ~~~^~~~~
ZeroDivisionError: float division by zero

Process finished with exit code 1

(Jul-25-2023, 11:04 AM)deanhystad Wrote:

(Jul-25-2023, 08:28 AM)Gribouillis Wrote: You could also try this

import atexit
import vpython
atexit.unregister(vpython.Exit)

Exit is not exposed through the module interface.

I did find this neat trick to get a list of registered atexit functions.

https://stackoverflow.com/questions/16042463/how-can-i-get-the-list-of-registered-atexit-functions-in-python3

So you could write this:

import vpython
import atexit

def unregister_by_name(name):
    funs = []

    class Capture:
        def __eq__(self, other):
            funs.append(other)
            return False

    c = Capture()
    atexit.unregister(c)
    for func in funs:
        if func.__name__ == name:
            atexit.unregister(func)

unregister_by_name("Exit")

It is easier to edit the vpython.py file. I wish I could fine something about the intention behind Exit().

(Jul-25-2023, 12:42 PM)deanhystad Wrote: The library works. It just has an ugly exit behavior. You'll be able to use it just fine, making all kinds of pretty pictures and animations, and all weill be well until your program quits. That is when Exit gets called. When used in a notebook you wouldn't see this until you closed the notebook. It a web page you wouldn't see it at all.