RadioButton value equals None when set to False

[knack-shawn]

Describe the bug
When a RadioButton options value should be set to False, it evaluates to None

To Reproduce
mcve.py

#!/usr/bin/env python3

from asciimatics.widgets import Frame, Layout, RadioButtons, Button
from asciimatics.scene import Scene
from asciimatics.screen import Screen
from asciimatics.exceptions import ResizeScreenError, StopApplication
import sys, time



class Simple(Frame):
    def __init__(self, screen):
        super().__init__(screen, screen.height,
                         screen.width)
        self.layout = Layout([1], fill_frame=True)
        self.add_layout(self.layout)
        self.rb = RadioButtons(label=('example_button'), options=[ (("True"),True) , (('False'),False)])
        self.layout.add_widget(self.rb)
        check_value = Button('check_value', self._store_val)
        self.layout.add_widget(check_value)
        self.fix()
    
    def _store_val(self):
        value = self.rb._value
        time.sleep(1)



def demo(screen, scene):
    scenes = [
        Scene([Simple(screen)], -1, name="example")
    ]

    screen.play(scenes, stop_on_resize=True, start_scene=scene, allow_int=True)

last_scene = None
while True:
    try:
        Screen.wrapper(demo, catch_interrupt=True, arguments=[last_scene])
        sys.exit(0)
    except ResizeScreenError as e:
        last_scene = e.scene

Expected behavior
I would expect rb.value = False. I would like to be able to get a boolean

System details (please complete the following information):

• OS and version: Rocky Linux 8.5
• Python version: Python 3.6.8
• Python distribution: standard python3.6 install
• Asciimatics version: 1.14.0

Additional context
quick fix in widgets/radiobuttons.py line 115

#This will not allow a radio button to be set to False
self._value = new_value if new_value else None

=>

self._value = new_value

[peterbrittain]

Strictly speaking, your mcve is accessing a private field. Your application should be using self.rb.value (note the lack of underscore). If you make that change, the code works as expected. That said, I'm not entirely happy with this code, so I'll tweak it to be more consistent in its internal state.