GNU bug report logs - #75171
30.0.50; Checklist widget inside a group does not initialize correctly

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From: Mauro Aranda <maurooaranda <at> gmail.com>
To: Al Haji-Ali <abdo.haji.ali <at> gmail.com>, 75171 <at> debbugs.gnu.org
Subject: bug#75171: 30.0.50; Checklist widget inside a group does not initialize correctly
Date: Mon, 6 Jan 2025 12:14:36 -0300

Mauro Aranda <maurooaranda <at> gmail.com> writes:

> Al Haji-Ali <abdo.haji.ali <at> gmail.com> writes:
>
>> On 02/01/2025, Mauro Aranda wrote:
>>
>>> Al Haji-Ali <abdo.haji.ali <at> gmail.com> writes:
>>> This is intended behavior, AFAIU.  The parent can override values for
>>> the children, and that way we can recreate widgets with new values just
>>> by changing the values of the parent.
>>
>> I was aware of this behaviour for the group, but I didn't twig the
>> consequence on a checklist.
>>
>> I have to say that I find it a bit counter-intuitive. Also the fact
>> that there is no way to set the value of a checklist without repeating
>> it in the group is somewhat awkward (certainly it will complicate my
>> implementation)
>
> Note that you don't necessarily need to repeat it in the checklist
> widget.  In my example, you only need to pass the :value in group:
>
> (defun widget-test ()
>   (let ((items '((item :format "%[One%] " :value 1)
>                  (item :format "%[Two%] " :value 2)
>                  (item :format "%[Three%] " :value 3))))
>     (widget-create
>      'group
>      :value '(2 (1 2))
>      (append '(radio-button-choice
>                :format "Not inline radio:\n%v\n")
>              items)
>      (append '(checklist
>                :format "Not inline checks:\n%v\n")
>              items)))
>   (widget-setup))
>
> When created, radio-button-choice will get its :value set to 2 and
> checklist will get it set to (1 2).
>
>> and a bit inconsistent since setting the value of the
>> checklist after the group creation would override the value of the
>> group. A fix, or a some way, that would prevents the group from
>> overriding the values of the children would be useful, IMO.
>>
>> With that being said, this issue should probably be closed as "not a
>> bug".
>
> I'd like to take some time to study this and see if there's a way to
> improve the situation.

Making the group widget create its children with their default
values is easy, by testing if it has a explicit nil value or not.  But
since it has worked this way forever, I wouldn't suggest changing it.

I think that specifying the :value in the group widget is the way that
the group widget it's supposed to work.  There are ways to derive a
widget from it that doesn't enforce it, so I'm inclined to mark this as
notabug.

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