_default is never updated after combo.clear() is called

I have 2 examples shown below which create a combo widget, clears out its contents and then rebuilds the combo’s contents. After doing so, calling select_default() fails because _default was never restored from the original value when the combo was originally inited.

Here is the warning output:

------------------------------------------------------------
*** GUIZERO WARNING ***
[Combo] object with options  ['4', '5', '6']
Unable to select default option as doesnt exists in Combo
------------------------------------------------------------

Before pressing the button:

After pressing the button:

Example 1:

from guizero import App, Combo, PushButton


class ComboBug:
    def __init__(self):
        app = App(title="Hello world")
        self.items1 = ['1', '2', '3']
        self.items2 = ['4', '5', '6']

        self.the_combo = Combo(app, options=self.items1)
        self.the_button = PushButton(app, text='Push Me', command=self.switch_items)

        app.display()

    def switch_items(self):
        self.the_combo.clear()
        count = 0
        for item in self.items2:
            self.the_combo.insert(count, item)
            count += 1
        self.the_combo.select_default()


ComboBug()

Example 2:

from guizero import App, Combo, PushButton


class ComboBug2:
    def __init__(self):
        app = App(title="Hello world")
        self.items1 = ['1', '2', '3']
        self.items2 = ['4', '5', '6']

        self.the_combo = Combo(app, options=self.items1)
        self.the_button = PushButton(app, text='Push Me', command=self.switch_items)

        app.display()

    def switch_items(self):
        self.the_combo.clear()
        for item in self.items2:
            self.the_combo.append(item)
        self.the_combo.select_default()


ComboBug2()

[MrYsLab]

Ok, I would prefer to go with whatever you are most comfortable with. Thanks. I am not sure if want me to close this or not, just close it or let me know and I will do it. Thanks.

[martinohanlon]

In scenario 2 (when a user selects a default at init), I am against changing the default because I am making choices about what the user wants.

I could change guizero so that it reverts the default to the first item in the list if the default is removed, but who is to say the user wont put it default option back in…

Its also consistent with scenario 1 - the user is “telling” guizero the default is the first option and that is never changed, the same with scenario 2, they tell guizero what the default is and then it never changes.