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TextStim causes RuntimeError: generator raised StopIteration

Hi all,

I’m working on my first experiment with Psychopy 3, and I keep getting an error when I try to start an instance of visual.TextStim. I’m running the standalone Psychopy v3.1.5 on Ubuntu 18.04.3 LTS. Here’s a minimal example that reproduces the error on my machine:

from psychopy import visual, core, data, event, monitors

win = visual.Window((500, 500),
                    fullscr=False,
                    color=(0, 0, 0),
                    colorSpace='rgb',
                    allowGUI=False)

text_stim = visual.TextStim(win, pos=(0, 0), text='hello')

text_stim.draw()
win.flip()
core.wait(4)
win.close()

And here’s the full traceback in case it’s helpful:

Traceback (most recent call last):
  File "/home/local/ADF/brookshg/anaconda3/lib/python3.7/site-packages/pyglet/text/runlist.py", line 408, in ranges
    starts[i], ends[i], values[i] = next(iterator)
StopIteration

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/home/local/ADF/brookshg/Documents/projects/saccades-attention/tests/textstim/textstim_test.py", line 13, in <module>
    text_stim = visual.TextStim(win, pos=(0, 0), text='hello')
  File "/home/local/ADF/brookshg/anaconda3/lib/python3.7/site-packages/PsychoPy-3.1.5-py3.7.egg/psychopy/visual/text.py", line 209, in __init__
    self.setText(text, log=False)
  File "/home/local/ADF/brookshg/anaconda3/lib/python3.7/site-packages/PsychoPy-3.1.5-py3.7.egg/psychopy/visual/text.py", line 354, in setText
    setAttribute(self, 'text', text, log)
  File "/home/local/ADF/brookshg/anaconda3/lib/python3.7/site-packages/PsychoPy-3.1.5-py3.7.egg/psychopy/tools/attributetools.py", line 141, in setAttribute
    setattr(self, attrib, value)
  File "/home/local/ADF/brookshg/anaconda3/lib/python3.7/site-packages/PsychoPy-3.1.5-py3.7.egg/psychopy/tools/attributetools.py", line 32, in __set__
    newValue = self.func(obj, value)
  File "/home/local/ADF/brookshg/anaconda3/lib/python3.7/site-packages/PsychoPy-3.1.5-py3.7.egg/psychopy/visual/text.py", line 345, in text
    self._setTextShaders(text)
  File "/home/local/ADF/brookshg/anaconda3/lib/python3.7/site-packages/PsychoPy-3.1.5-py3.7.egg/psychopy/visual/text.py", line 364, in _setTextShaders
    width=self._wrapWidthPix)  # width of the frame
  File "/home/local/ADF/brookshg/anaconda3/lib/python3.7/site-packages/pyglet/font/text.py", line 338, in __init__
    group=self._group)
  File "/home/local/ADF/brookshg/anaconda3/lib/python3.7/site-packages/pyglet/text/layout.py", line 810, in __init__
    self.document = document
  File "/home/local/ADF/brookshg/anaconda3/lib/python3.7/site-packages/pyglet/text/layout.py", line 919, in _set_document
    self._init_document()
  File "/home/local/ADF/brookshg/anaconda3/lib/python3.7/site-packages/pyglet/text/layout.py", line 1020, in _init_document
    self._update()
  File "/home/local/ADF/brookshg/anaconda3/lib/python3.7/site-packages/pyglet/text/layout.py", line 956, in _update
    lines = self._get_lines()
  File "/home/local/ADF/brookshg/anaconda3/lib/python3.7/site-packages/pyglet/text/layout.py", line 932, in _get_lines
    glyphs = self._get_glyphs()
  File "/home/local/ADF/brookshg/anaconda3/lib/python3.7/site-packages/pyglet/text/layout.py", line 1055, in _get_glyphs
    for start, end, (font, element) in runs.ranges(0, len(text)):
RuntimeError: generator raised StopIteration

Thanks in advance for any suggestions!

geoff

Update!

I’ve solved the problem. It appears in the pyglet file runlist.py because of a change in the way Python 3.7 handles a StopIteration. I’ve submitted a pull request to the pyglet github repository.

In case anyone else runs into the same problem, you can fix it by replacing line 408 in pyglet/text/runlist.py. Delete this line:

                    starts[i], ends[i], values[i] = next(iterator) 

And replace it with this:

                    try:
                        starts[i], ends[i], values[i] = next(iterator)
                    except StopIteration:
                        return