Kivy Inspector tool usage gives ReferenceError: weakly-referenced object no longer exists

[Shoumik Das]

Hi! I have a pretty odd situation at hand. I have implemented a custom drop-down in a Kivy app which runs fine and the behaviour as intended. However, when I run the same code by invoking the inspector tool and then try to select the drop-down, it returns a weak reference error.

Here are the relevant sections of the code:

Python

from kivy.app import App

from kivy.uix.widget import Widget

from kivy.uix.boxlayout import BoxLayout

from kivy.uix.floatlayout import FloatLayout

from kivy.uix.anchorlayout import AnchorLayout

from kivy.uix.screenmanager import ScreenManager, Screen, CardTransition

from kivy.uix.button import Button

from kivy.uix.behaviors import ButtonBehavior

from kivy.uix.image import Image

from kivy.uix.label import Label

from kivy.uix.actionbar import ActionBar, ActionItem

from kivy.uix.textinput import TextInput

from kivy.properties import NumericProperty, StringProperty

from kivy.uix.dropdown import DropDown

from kivy.uix.popup import Popup

from calendar_ui import DatePicker, CalendarWidget

class CustomTextInput(TextInput):

# Numeric property defined for use in both Python and Kivy (binding)

max_characters = NumericProperty(0)

# Override the default behaviour of the insert_text method

def insert_text(self, substring, from_undo=False):

if len(self.text)==self.max_characters and self.max_characters>0:

substring=""

TextInput.insert_text(self, substring, from_undo)

class ImageButton(ButtonBehavior, Image):

pass

class CustomActionButton(ImageButton, ActionItem):

pass

class ImageLabel(BoxLayout):

source = StringProperty('atlas://data/images/defaulttheme/audio-volume-high')

text = StringProperty('default text')

class ImageLabelButton(ButtonBehavior, ImageLabel):

pass

class ImageLabelButtonTop(ButtonBehavior, ImageLabel):

pass

class SivaLoginScreen(Screen):

    def t_authentication(self):

App.get_running_app().root.current='verify_screen'

App.get_running_app().root.transition.direction='left'

def l_authentication(self):

App.get_running_app().root.current='verify_screen'

App.get_running_app().root.transition.direction='left'

class SivaVerifyScreen(Screen):

def back_to_login(self):

App.get_running_app().root.current='login_screen'

App.get_running_app().root.transition.direction='right'

def code_verification(self):

App.get_running_app().root.current='status_screen'

App.get_running_app().root.transition.direction='left'

class SivaStatusScreen(Screen):

def to_statusscreen(self):

App.get_running_app().root.current='status_screen'

App.get_running_app().root.transition.direction='left'

def to_accountsscreen(self):

App.get_running_app().root.current='accounts_screen'

App.get_running_app().root.transition.direction='left'

def to_botscreen(self):

App.get_running_app().root.current='bot_screen'

App.get_running_app().root.transition.direction='left'

def to_logout(self):

App.get_running_app().root.current='login_screen'

App.get_running_app().root.transition.direction='right'

def new_status_entry(self):

App.get_running_app().root.current='newstatus_screen'

App.get_running_app().root.transition.direction='left'

class SivaAccountsScreen(Screen):

def to_statusscreen(self):

App.get_running_app().root.current='status_screen'

App.get_running_app().root.transition.direction='right'

def to_accountsscreen(self):

App.get_running_app().root.current='accounts_screen'

App.get_running_app().root.transition.direction='left'

def to_botscreen(self):

App.get_running_app().root.current='bot_screen'

App.get_running_app().root.transition.direction='left'

def to_logout(self):

App.get_running_app().root.current='login_screen'

App.get_running_app().root.transition.direction='right'

class SivaBotScreen(Screen):

def to_statusscreen(self):

App.get_running_app().root.current='status_screen'

App.get_running_app().root.transition.direction='right'

def to_accountsscreen(self):

App.get_running_app().root.current='accounts_screen'

App.get_running_app().root.transition.direction='right'

def to_botscreen(self):

App.get_running_app().root.current='bot_screen'

App.get_running_app().root.transition.direction='left'

def to_logout(self):

App.get_running_app().root.current='login_screen'

App.get_running_app().root.transition.direction='right'

class SivaTermsScreen(Screen):

pass

class NewStatusScreen(Screen):

def back_to_status(self):

App.get_running_app().root.current='status_screen'

App.get_running_app().root.transition.direction='right'

class SivaScreenManager(ScreenManager):

pass

class SivaApp(App):

def build(self):

# Initialize root widget

# Screen Manager Instance

ssm=SivaScreenManager(transition=CardTransition())

# Login Screen Instance

sls=SivaLoginScreen()

# Verify Screen Instance

svs=SivaVerifyScreen()

# Status Screen Instance

sss=SivaStatusScreen()

# Accounts Screen Instance

sas=SivaAccountsScreen()

# Bot Screen Instance

sbs=SivaBotScreen()

# New Status Screen Instance

nss=NewStatusScreen()

# Create widget tree. Screen Manager is the root widget.

ssm.add_widget(sls)

ssm.add_widget(svs)

ssm.add_widget(sss)

ssm.add_widget(sas)

ssm.add_widget(sbs)

ssm.add_widget(nss)

return ssm

if __name__ == '__main__':

# Run application

SivaApp().run()

Kivy

<Label>:

-font_name: 'roboto/Roboto-Regular.ttf'

<ImageButton>:

keep_ratio: True

<CustomTextInput>:

use_bubble: True

use_handles: True

<CustomActionButton>:

size_hint_x: 0.05

size_hint_min_x: 48

<SivaLoginScreen>:

name: 'login_screen'

canvas.before:

Color:

rgba: 195/255, 60/255, 35/255, 1

Rectangle:

pos: self.pos

size: self.size

BoxLayout:

id: login_layout

orientation: 'vertical'

size_hint: 0.4, 0.8

pos_hint: {'center_x':0.5, 'center_y':0.5}

Image:

id: login_logo_siva

source: 'images/sivalogo1.png'

keep_ratio: True

BoxLayout:

id: login_slogan_box

orientation: 'vertical'

Label:

id: login_label_space1

Label:

id: login_label_siva

markup: True

font_name: 'roboto/Roboto-Medium.ttf'

text: '[color=#FDFD98]S[/color][color=#B29DD9]I[/color][color=#77DD77]V[/color][color=#779ECB]A[/color]'

font_size: '40sp'

Label:

id: login_label_space2

Label:

id: login_label_slogan1

markup: True

font_name: 'roboto/Roboto-Regular.ttf'

text: '[color=#FDFD98]ABCD EFGH[/color]'

font_size: '13sp'

Label:

id: login_label_slogan2

markup: True

font_name: 'roboto/Roboto-Regular.ttf'

text: '[color=#FDFD98]IJKL MNOP[/color]'

font_size: '13sp'

BoxLayout:

id: login_button_layout

orientation: 'horizontal'

spacing: 1

ImageButton:

id: t_button

source: {'normal': 'images/t-circled-96.png', 'down': 'images/t-96.png'} [self.state]

on_release: root.t_authentication()

ImageButton:

id: l_button

source: {'normal': 'images/l-circled-96.png', 'down': 'images/l-2-96.png'} [self.state]

on_release: root.l_authentication()

<SivaVerifyScreen>:

name: 'verify_screen'

canvas.before:

Color:

rgba: 195/255, 60/255, 35/255, 1

Rectangle:

pos: self.pos

size: self.size

AnchorLayout:

id: verify_backbtn_layout

anchor_x: 'left'

anchor_y: 'top'

ImageButton:

id: verify_back_button

size_hint: 0.1, 0.1

source: {'normal': 'images/chevron-left-96.png', 'down': 'images/chevron-left-96.png'} [self.state]

on_release: root.back_to_login()

BoxLayout:

id: verify_layout

orientation: 'vertical'

size_hint: 0.6, 0.6

pos_hint: {'center_x':0.5, 'center_y':0.5}

Label:

id: verify_label

markup: True

font_name: 'roboto/Roboto-Regular.ttf'

text: 'Verification Code'

font_size: '16sp'

BoxLayout:

id: verify_textinput

orientation: 'vertical'

CustomTextInput:

id: verify_inputbox

multiline: False

focus: True

hint_text: '1234567'

font_size: '30sp'

max_characters: 10

input_filter: 'int'

Label:

id: verify_space1

BoxLayout:

id: verify_btn_layout

orientation: 'horizontal'

Label:

id: placeholder_label1

ImageButton:

id: verify_button

source: {'normal': 'images/lock-96.png', 'down': 'images/privacy-96.png'} [self.state]

on_release: root.code_verification()

Label:

id: placeholder_label2

<SivaStatusScreen>:

name: 'status_screen'

canvas.before:

Color:

rgba: 255/255, 255/255, 255/255, 1

Rectangle:

pos: self.pos

size: self.size

AnchorLayout:

id: status_add

anchor_x: 'right'

anchor_y: 'bottom'

ImageButton:

id: status_addbtn

source: {'normal': 'images/plus-96.png', 'down': 'images/plusblue-96.png'} [self.state]

size_hint: 0.2, 0.2

on_release: root.new_status_entry()

BoxLayout:

id: status_layout

orientation: 'vertical'

BoxLayout:

id: actionbar_layout

size_hint_y: None

height: 48

ActionBar:

id: status_actionbar

pos_hint: {'top': 1}

background_image: ''

background_color: 195/255, 60/255, 35/255, 1

ActionView:

use_separator: True

ActionPrevious:

title: 'SIVA'

with_previous: False

ActionOverflow:

CustomActionButton:

id: status-button

important: True

source: {'normal': 'images/communicationgreen-48.png', 'down': 'images/communication-48.png'} [self.state]

on_release: root.to_statusscreen()

CustomActionButton:

id: accounts-button

important: True

source: {'normal': 'images/key-48.png', 'down': 'images/keygreen-48.png'} [self.state]

on_release: root.to_accountsscreen()

CustomActionButton:

id: bot-button

important: True

source: {'normal': 'images/bot-48.png', 'down': 'images/botgreen-48.png'} [self.state]

on_release: root.to_botscreen()

CustomActionButton:

id: logout-button

important: True

source: {'normal': 'images/shutdown-48.png', 'down': 'images/shutdowngreen-48.png'} [self.state]

on_release: root.to_logout()

BoxLayout:

id: status_display

orientation: 'vertical'

BoxLayout:

id: status_label

size_hint_y: None

height: 40

BoxLayout:

orientation: 'horizontal'

BoxLayout:

orientation: 'horizontal'

Image:

keep_ratio: True

source: 'images/communication-48.png'

Label:

text: 'Status'

markup: True

color: 0, 0, 0, 1

ImageLabelButtonTop:

# conflict in the on_release defined for ImageLabelButton and this instance.

id: parent_button

source: 'images/expand-arrow-48.png'

text: 'User'

on_release:

# root.add_dd_values()

dropdown.open(self)

on_parent: dropdown.dismiss()

size_hint_y: None

height: '40dp'

DropDown:

id: dropdown

on_select:

# args is a reserved keyword which returns only two values: object alias (0) and data (1).

parent_button.text = args[1][0]

parent_button.source = args[1][1]

# Invoked inside dropdown

# root - Screen, self - DropDown object

ImageLabelButton:

source: 'images/t-circled-48.png'

text: 'Test'

ImageLabelButton:

source: 'images/l-circled-48.png'

text: 'Load'

BoxLayout:

id: status_content

<SivaAccountsScreen>:

name: 'accounts_screen'

canvas.before:

Color:

rgba: 255/255, 255/255, 255/255, 1

Rectangle:

pos: self.pos

size: self.size

AnchorLayout:

id: accounts_add

anchor_x: 'right'

anchor_y: 'bottom'

ImageButton:

id: accounts_addbtn

source: {'normal': 'images/plus-96.png', 'down': 'images/plusblue-96.png'} [self.state]

size_hint: 0.2, 0.2

BoxLayout:

id: accounts_layout

orientation: 'vertical'

BoxLayout:

id: actionbar_layout2

size_hint_y: None

height: 48

ActionBar:

id: accounts_actionbar

pos_hint: {'top': 1}

background_image: ''

background_color: 195/255, 60/255, 35/255, 1

ActionView:

use_separator: True

ActionPrevious:

title: 'S.I.V.A'

with_previous: False

ActionOverflow:

CustomActionButton:

id: status-button2

important: True

source: {'normal': 'images/communication-48.png', 'down': 'images/communicationgreen-48.png'} [self.state]

on_release: root.to_statusscreen()

CustomActionButton:

id: accounts-button2

important: True

source: {'normal': 'images/keygreen-48.png', 'down': 'images/key-48.png'} [self.state]

on_release: root.to_accountsscreen()

CustomActionButton:

id: bot-button2

important: True

source: {'normal': 'images/bot-48.png', 'down': 'images/botgreen-48.png'} [self.state]

on_release: root.to_botscreen()

CustomActionButton:

id: logout-button2

important: True

source: {'normal': 'images/shutdown-48.png', 'down': 'images/shutdowngreen-48.png'} [self.state]

on_release: root.to_logout()

BoxLayout:

id: accounts_display

<SivaBotScreen>:

name: 'bot_screen'

canvas.before:

Color:

rgba: 255/255, 255/255, 255/255, 1

Rectangle:

pos: self.pos

size: self.size

AnchorLayout:

id: bot_add

anchor_x: 'right'

anchor_y: 'bottom'

ImageButton:

id: bot_addbtn

source: {'normal': 'images/plus-96.png', 'down': 'images/plusblue-96.png'} [self.state]

size_hint: 0.2, 0.2

BoxLayout:

id: bot_layout

orientation: 'vertical'

BoxLayout:

id: actionbar_layout3

size_hint_y: None

height: 48

ActionBar:

id: bot_actionbar

pos_hint: {'top': 1}

background_image: ''

background_color: 195/255, 60/255, 35/255, 1

ActionView:

use_separator: True

ActionPrevious:

title: 'SIVA'

with_previous: False

ActionOverflow:

CustomActionButton:

id: status-button3

important: True

source: {'normal': 'images/communication-48.png', 'down': 'images/communicationgreen-48.png'} [self.state]

on_release: root.to_statusscreen()

CustomActionButton:

id: accounts-button3

important: True

source: {'normal': 'images/key-48.png', 'down': 'images/keygreen-48.png'} [self.state]

on_release: root.to_accountsscreen()

CustomActionButton:

id: bot-button3

important: True

source: {'normal': 'images/botgreen-48.png', 'down': 'images/bot-48.png'} [self.state]

on_release: root.to_botscreen()

CustomActionButton:

id: logout-button3

important: True

source: {'normal': 'images/shutdown-48.png', 'down': 'images/shutdowngreen-48.png'} [self.state]

on_release: root.to_logout()

BoxLayout:

id: bot_display

<NewStatusScreen>:

name: 'newstatus_screen'

canvas.before:

Color:

rgba: 255/255, 255/255, 255/255, 1

Rectangle:

pos: self.pos

size: self.size

AnchorLayout:

id: newstatus_backbtn_layout

anchor_x: 'left'

anchor_y: 'top'

ImageButton:

id: newstatus_back_button

size_hint: 0.1, 0.1

source: {'normal': 'images/back-96.png', 'down': 'images/back-96.png'} [self.state]

on_release: root.back_to_status()

BoxLayout:

id: newstatus_layout

orientation: 'vertical'

size_hint: 0.8, 0.9

pos_hint: {'center_x':0.5, 'center_y':0.5}

spacing: 2

BoxLayout:

orientation: 'vertical'

CustomTextInput:

id: status_text

size_hint_y: 0.8

multiline: True

focus: True

hint_text: 'Enter your new status message'

font_size: '20sp'

max_characters: 280

Label:

id: chars_left

size_hint_y: 0.2

markup: True

text: str(len(status_text.text))+"/280"

color: 0/255, 0/255, 0/255, 1

text_size: self.size

halign: 'right'

valign: 'top'

BoxLayout:

spacing: 2

orientation: 'horizontal'

Button:

text: 'Button1'

Button:

text: 'Button2'

BoxLayout:

orientation: 'horizontal'

spacing: 5

DatePicker:

pHint: 0.9,0.8

BoxLayout:

spacing: 5

orientation: 'vertical'

canvas.after:

Color:

rgba: 128/255, 128/255, 128/255, 1

Line:

width: dp(1)

rectangle: (*self.pos, self.width, self.height)

Label:

id: time_label

text: 'TIME'

font_size: '11sp'

font_name: 'roboto/Roboto-Medium.ttf'

markup: True

color: 0, 0, 0, 1

Slider:

id: hrs_slider

min: 0

max: 23

step: 1

cursor_size: 25, 25

value: 18

value_track: True

value_track_color: 254/255, 107/255, 100/255, 1

orientation: 'horizontal'

Label:

text:'HH: '+str(int(hrs_slider.value))

markup: True

font_size: '11sp'

font_name: 'roboto/Roboto-Medium.ttf'

color: 0, 0, 0, 1

halign: 'center'

valign: 'middle'

Slider:

id: mins_slider

min: 0

max: 59

step: 1

cursor_size: 25, 25

value: 30

value_track: True

value_track_color: 254/255, 107/255, 100/255, 1

orientation: 'horizontal'

Label:

text:'MM: '+str(int(mins_slider.value))

markup: True

font_size: '11sp'

font_name: 'roboto/Roboto-Medium.ttf'

color: 0, 0, 0, 1

halign: 'center'

valign: 'middle'

BoxLayout:

orientation: 'horizontal'

ImageButton:

source: {'normal': 'images/picture-96.png', 'down': 'images/picture-green-96.png'} [self.state]

ImageButton:

source: {'normal': 'images/save-96.png', 'down': 'images/save-close-96.png'} [self.state]

<ImageLabel>:

orientation: 'horizontal'

size_hint_y: None

height: '40dp'

spacing: 1

Image:

size_hint_x: 0.3

keep_ratio: True

source: root.source  # root - ImageLabel

Label:

size_hint_x: 0.7

markup: True

text: root.text  # root - ImageLabel

color: 0, 0, 0, 1

<ImageLabelButton>:

on_release:

# Tuple returned in dropdown.select() method to pass two values bundled as one.

app.root.get_screen('status_screen').ids.dropdown.select((self.text, self.source))

# Invoked inside ImageLabelButton rule

# app.root - Screen, root - ImageLabelButton object, self - ImageLabelButton object

It seems the following statement is causing an issue when the inspector tool is invoked:

dropdown.open(self)

The error screenshot is shown below. The app shuts down abruptly with the following error when I click on the drop-down:

If I run the same code without the Kivy inspector tool, the app runs fine. Can someone please advise what I might be doing wrong here?

Thanks in advance

[Robert Flatt]

From the inspector docs:

Warning

This module is highly experimental, use it with care.

The error is about garbage collection.

There is a known weakref issue with Kivy 1.11.1 which can appear with Python 3.8's garbage collection.

The workaround for that is Kivy==2.0.0rc3

[Giù sé]

In my case kivy==master solved the weakref issues

[Shoumik Das]

Thanks for the responses. I am glad that it is not an issue with the code.