Wrapper for simple dialog/prompt using kivy

askdialog.py

from kivy.logger import Logger
from kivymd.app import MDApp
from kivymd.uix.screen import MDScreen
from kivymd.uix.button import MDFlatButton
from kivymd.uix.boxlayout import MDBoxLayout
from kivymd.uix.dialog.dialog import MDDialog
from kivymd.uix.textfield.textfield import MDTextField


class AskDialog:

    def __init__(self, title, callback, hint):
        self._callback = callback
        hint_text = hint or ""
        self._dialog_text = MDTextField(hint_text=hint_text)
        self.dialog = MDDialog(
                title=title,
                type="custom",
                pos_hint={"center_x": .5, "center_y": .5},
                buttons=[
                    MDFlatButton(text="Cancel", on_release=lambda x: self.pressed_cancel(x)),
                    MDFlatButton(text="OK", on_release=lambda x: self.pressed_ok(x))
                    ],
                content_cls=MDBoxLayout(
                    self._dialog_text,
                    orientation="vertical",
                    spacing="12dp",
                    size_hint_y=None,
                    height="120dp",
                    )
                )

    def launch(self):
        self.dialog.open()

    def pressed_cancel(self, buttonid):
        Logger.info("pressed cancel")
        self.dialog.dismiss()

    def pressed_ok(self, buttonid):
        Logger.info("pressed ok")
        self._callback(self._dialog_text.text)
        self.dialog.dismiss()

    @classmethod
    def ask(cls, prompt, callback, hint=None):
        dialog = cls(title=prompt, callback=callback, hint=hint)
        dialog.launch()


class TestApp(MDApp):

    def build(self):
        self.theme_cls.theme_style = "Dark"
        self.theme_cls.primary_palette = "Orange"
        return (
            MDScreen(
                MDFlatButton(
                    text="Cause a popup",
                    line_color=(0, 0, 0, 0),
                    pos_hint={"center_x": .5, "center_y": .3},
                    on_release=self.cause_a_popup
                ),
                MDFlatButton(
                    text="Exit by pressing this button",
                    line_color=(0, 0, 0, 0),
                    pos_hint={"center_x": .5, "center_y": .6},
                    on_release=self.stop
                )
            )
        )

    def cause_a_popup(self, _):
        Logger.info("Caused a Popup")
        AskDialog.ask("Enter some text:", self.when_text_entered)

    def when_text_entered(self, entered_text):
        Logger.info(f"At the popup, you entered {entered_text!r}")


if __name__ == '__main__':
    TestApp().run()

Pressing the buttons doesn't work.

FWIW, the answer was wrapping the on_release values in a lambda. Weird weird weird.