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From: Eli Zaretskii <eliz@gnu.org>
To: Drew Adams <drew.adams@oracle.com>
Cc: 51595@debbugs.gnu.org
Subject: bug#51595: 26.3; Face attribute value `unspecified' in `defface' breaks Customize UI
Date: Thu, 04 Nov 2021 08:49:54 +0200	[thread overview]
Message-ID: <83wnlofm99.fsf@gnu.org> (raw)
In-Reply-To: <SJ0PR10MB5488ED8544FC15488361DCD4F38C9@SJ0PR10MB5488.namprd10.prod.outlook.com> (message from Drew Adams on Wed, 3 Nov 2021 21:09:41 +0000)

> From: Drew Adams <drew.adams@oracle.com>
> Date: Wed, 3 Nov 2021 21:09:41 +0000
> 
> emacs -Q
> 
> (defface foo '((t :background "LightBlue")) "DOC ..." :group 'faces)
> (defface bar '((t :foreground unspecified :background "LightBlue"))
>   "DOC..." :group 'faces)

Don't do that.  Using 'unspecified' in user code is an error.  Patches
to the docs to that effect are welcome.

> The doc (Elisp manual) draws no such distinction - speaks of no such
> limitation.  It just lists `unspecified' as one of the possible face
> attributes:
> 
>   "Apart from the values given below, each face attribute can have the
>    value 'unspecified'."

"Can have" is a notice to Lisp programmers to expect such a value, it
is not an invitation to use it in defface or any other face specs.
the correct way of not specifying a value is to use nil or (better)
not to mention the attribute at all.  Think about how Emacs merges
faces, and you will understand why.





  parent reply	other threads:[~2021-11-04  6:49 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-11-03 21:09 bug#51595: 26.3; Face attribute value `unspecified' in `defface' breaks Customize UI Drew Adams
2021-11-03 22:13 ` Stefan Kangas
2021-11-04  6:49 ` Eli Zaretskii [this message]
2021-11-04 17:58   ` Lars Ingebrigtsen

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