npyscreen 4.10.5 does not works on python 3.8

[yhojann-cl]

By example:

#!/usr/bin/env python3
# -*- coding: utf-8 -*-

import npyscreen

class MainForm(npyscreen.FormBaseNew):
    def create(self):
        self.add(npyscreen.BoxTitle, name="BoxTitle")

class MainController(npyscreen.StandardApp):
    def onStart(self):
        self.addForm('MAIN', MainForm, name='Test')

class MainCLS(object):
    def __init__(self):
        mainController = MainController()
        mainController.run()

if __name__ == '__main__':
    MainCLS()

The results:

$ lsb_release -a
No LSB modules are available.
Distributor ID:	Ubuntu
Description:	Ubuntu 20.04.1 LTS
Release:	20.04
Codename:	focal
$ python3 --version
Python 3.8.2
$ pip3 install npyscreen
Requirement already satisfied: npyscreen in /home/.../.local/lib/python3.8/site-packages (4.10.5)
$ python3 test.py
Traceback (most recent call last):
  File "/home/.../.local/lib/python3.8/site-packages/npyscreen/apNPSApplicationEvents.py", line 16, in get
    yield self.interal_queue.pop()
IndexError: pop from an empty deque

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/.../.local/lib/python3.8/site-packages/npyscreen/apNPSApplicationEvents.py", line 18, in get
    raise StopIteration
StopIteration

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

Traceback (most recent call last):
  File "test.py", line 20, in <module>
    MainCLS()
  File "test.py", line 17, in __init__
    mainController.run()
  File "/home/.../.local/lib/python3.8/site-packages/npyscreen/apNPSApplication.py", line 30, in run
    return npyssafewrapper.wrapper(self.__remove_argument_call_main)
  File "/home/.../.local/lib/python3.8/site-packages/npyscreen/npyssafewrapper.py", line 41, in wrapper
    wrapper_no_fork(call_function)
  File "/home/.../.local/lib/python3.8/site-packages/npyscreen/npyssafewrapper.py", line 97, in wrapper_no_fork
    return_code = call_function(_SCREEN)    
  File "/home/.../.local/lib/python3.8/site-packages/npyscreen/apNPSApplication.py", line 25, in __remove_argument_call_main
    return self.main()
  File "/home/.../.local/lib/python3.8/site-packages/npyscreen/apNPSApplicationManaged.py", line 172, in main
    self._THISFORM.edit()
  File "/home/.../.local/lib/python3.8/site-packages/npyscreen/fm_form_edit_loop.py", line 47, in edit
    self.edit_loop()
  File "/home/.../.local/lib/python3.8/site-packages/npyscreen/fm_form_edit_loop.py", line 38, in edit_loop
    self._widgets__[self.editw].edit()
  File "/home/.../.local/lib/python3.8/site-packages/npyscreen/wgboxwidget.py", line 150, in edit
    self.entry_widget.edit()
  File "/home/.../.local/lib/python3.8/site-packages/npyscreen/wgmultiline.py", line 581, in edit
    self.get_and_use_key_press()
  File "/home/.../.local/lib/python3.8/site-packages/npyscreen/wgwidget.py", line 575, in get_and_use_key_press
    return self.try_while_waiting()
  File "/home/.../.local/lib/python3.8/site-packages/npyscreen/wgwidget.py", line 560, in try_while_waiting
    self.parent.parentApp._internal_while_waiting()
  File "/home/.../.local/lib/python3.8/site-packages/npyscreen/apNPSApplicationEvents.py", line 41, in _internal_while_waiting
    self.process_event_queues(max_events_per_queue=self.max_events_per_queue)
  File "/home/.../.local/lib/python3.8/site-packages/npyscreen/apNPSApplicationEvents.py", line 51, in process_event_queues
    for event in queue.get(maximum=max_events_per_queue):
RuntimeError: generator raised StopIteration

[sur0g]

Got this on Ubuntu 20.04 LTS with Python 3.8.
Seems like it's more curses problem that npyscreen by itself (or it's just outdated).
I was able to fix it by wrapping this loop with try block at npyscreen.apNPSApplicationEvents.StandardApp.process_event_queues

    def process_event_queues(self, max_events_per_queue=None):
        for queue in self.event_queues.values():
+            try:
                for event in queue.get(maximum=max_events_per_queue):
                    self.process_event(event)
+            except (RuntimeError, StopIteration):
+                pass

I don't understand the issue's origins and this fix though.

[bartlomiejcieszkowski]

hit the same error, checked the code:
https://github.com/npcole/npyscreen/blob/master/npyscreen/apNPSApplicationEvents.py#L18
and it looks like its fixed on master for 2 years

the version on pypi is very old