First test program fails - There is no current event loop in thread 3

[John Mycroft]

I have just installed vpython (and --upgrade) on a Windows 10 laptop.  My first simple program :-

from vpython import *

box()

fails consistently with many error message lines that finish with

  File "C:\Python35\lib\asyncio\tasks.py", line 538, in ensure_future

    loop = events.get_event_loop()

  File "C:\Python35\lib\asyncio\events.py", line 626, in get_event_loop

    return get_event_loop_policy().get_event_loop()

  File "C:\Python35\lib\asyncio\events.py", line 572, in get_event_loop

    % threading.current_thread().name)

RuntimeError: There is no current event loop in thread 'Thread-3'.

I have vpython in my site-packages folder and as far as I can figure installation was 100% successful.  Any help ratefully accpted.  I did try running that test program directly on the glowscript.org website and it worked fine.

Cheers - John

[Craig Wiegert]

Hi John,

What version of python 3 do you have installed on your laptop? I ran
into similar error messages with python 3.5.2, but updating to python
3.5.3 (or 3.6.x) seemed to fix the problem for me.

Cheers,

- Craig

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[John Mycroft]

Hi, Craig

Yup - that did it - I upgraded to 3.6.2 and re-installed numpy (because of an error message) and I now have what looks like a working vpython.  Thanks for your help.  Incidentally, I plan to use vpython on my "tutorial day" (one day in five) of the intro Python course I teach in high school.  The first 4 periods of the week are spent teaching the syntax and all that boring stuff and the tutorial period is a kind of sandbox day where we go over tips & tricks, questions that need more than a quick 2 minute answer, experimenting time and so on.  (My principal calls this period "unprofessional").  vpython will fit in there very nicely.

Cheers - John

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[Bruce Sherwood]

As a result of this useful exchange I've changed the instructions at vpython.org to say the following about Python 3.5 (I had happened to test only with 3.5.3 and failed to notice the problem with 3.5.2):

You can run from IDLE or Spyder with Python 3.5 (3.5.3 or greater) or 3.6. You can start Spyder from a command prompt by typing "spyder", but you also have to go to Run > Configure and specify "Execute in a new dedicated Python console". Some Mac users have reported that running from IDLE or Spyder doesn't work, and the cause is under study. The following workaround, making and invoking a new environment, does work:

      conda create -n vpclean -c vpython vpython python=3
      source activate vpclean

Issue with Spyder: There is a new Spyder 3.2 that may not support the use of vpython. The Spyder developers are aware of the issue and have offered to address the problem.