A question about face-all-attributes

A question about face-all-attributes

[Xue Fuqiao]

Hi,

I'm experimenting with faces in Emacs Lisp now, but I don't understand
this piece of code:

  (face-all-attributes 'default)
    =>
  ((:family . unspecified) (:foundry . unspecified) (:width .
unspecified) (:height . unspecified) (:weight . unspecified) (:slant .
unspecified) (:underline . unspecified) (:overline . unspecified)
(:strike-through . unspecified) (:box . unspecified) (:inverse-video .
unspecified) (:foreground . unspecified) ...)

But:

  (describe-face 'default)
    =>
      Family: Ubuntu Mono
     Foundry: unknown
       Width: normal
      Height: 128
      ...

Why are the two results different?  I expected similar results from
them.  I searched ‘face-all-attributes’ but found no document matching
my query.  Can anyone point me in the right direction?

-- 
Best regards, Xue Fuqiao.
http://www.gnu.org/software/emacs/

Re: A question about face-all-attributes

[Eli Zaretskii]

> Date: Wed, 23 Oct 2013 21:49:28 +0800
> From: Xue Fuqiao <xfq.free@gmail.com>
> 
>   (face-all-attributes 'default)
>     =>
>   ((:family . unspecified) (:foundry . unspecified) (:width .
> unspecified) (:height . unspecified) (:weight . unspecified) (:slant .
> unspecified) (:underline . unspecified) (:overline . unspecified)
> (:strike-through . unspecified) (:box . unspecified) (:inverse-video .
> unspecified) (:foreground . unspecified) ...)
> 
> But:
> 
>   (describe-face 'default)
>     =>
>       Family: Ubuntu Mono
>      Foundry: unknown
>        Width: normal
>       Height: 128
>       ...
> 
> Why are the two results different?  I expected similar results from
> them.

If the results were similar, the existence of describe-face would not
have been justified.  It exists to show you what the default
attributes really will be.

Re: A question about face-all-attributes

[Xue Fuqiao]

On Wed, Oct 23, 2013 at 11:42 PM, Eli Zaretskii <eliz@gnu.org> wrote:
>>   (face-all-attributes 'default)
>>     =>
>>   ((:family . unspecified) (:foundry . unspecified) (:width .
>> unspecified) (:height . unspecified) (:weight . unspecified) (:slant .
>> unspecified) (:underline . unspecified) (:overline . unspecified)
>> (:strike-through . unspecified) (:box . unspecified) (:inverse-video .
>> unspecified) (:foreground . unspecified) ...)
>>
>> But:
>>
>>   (describe-face 'default)
>>     =>
>>       Family: Ubuntu Mono
>>      Foundry: unknown
>>        Width: normal
>>       Height: 128
>>       ...
>>
>> Why are the two results different?  I expected similar results from
>> them.
>
> If the results were similar, the existence of describe-face would not
> have been justified.  It exists to show you what the default
> attributes really will be.

Thanks, Eli.  But in (info "(elisp) Face Attributes"):

  An ‘unspecified’ attribute tells Emacs to refer instead to a parent
  face; or, failing that, to an underlying face.  The ‘default’ face
  must specify all attributes.

But all the attributes returned by face-all-attributes are
‘unspecified’, why?

-- 
Best regards, Xue Fuqiao.
http://www.gnu.org/software/emacs/

Re: A question about face-all-attributes

[Eli Zaretskii]

> Date: Thu, 24 Oct 2013 18:47:59 +0800
> From: Xue Fuqiao <xfq.free@gmail.com>
> Cc: help-gnu-emacs <help-gnu-emacs@gnu.org>
> 
> On Wed, Oct 23, 2013 at 11:42 PM, Eli Zaretskii <eliz@gnu.org> wrote:
> >>   (face-all-attributes 'default)
> >>     =>
> >>   ((:family . unspecified) (:foundry . unspecified) (:width .
> >> unspecified) (:height . unspecified) (:weight . unspecified) (:slant .
> >> unspecified) (:underline . unspecified) (:overline . unspecified)
> >> (:strike-through . unspecified) (:box . unspecified) (:inverse-video .
> >> unspecified) (:foreground . unspecified) ...)
> >>
> >> But:
> >>
> >>   (describe-face 'default)
> >>     =>
> >>       Family: Ubuntu Mono
> >>      Foundry: unknown
> >>        Width: normal
> >>       Height: 128
> >>       ...
> >>
> >> Why are the two results different?  I expected similar results from
> >> them.
> >
> > If the results were similar, the existence of describe-face would not
> > have been justified.  It exists to show you what the default
> > attributes really will be.
> 
> Thanks, Eli.  But in (info "(elisp) Face Attributes"):
> 
>   An ‘unspecified’ attribute tells Emacs to refer instead to a parent
>   face; or, failing that, to an underlying face.  The ‘default’ face
>   must specify all attributes.
> 
> But all the attributes returned by face-all-attributes are
> ‘unspecified’, why?

Evidently, the manual is blatantly wrong.  Unless this is an
unfortunate combination of using `unspecified' in the first sentence
and `specify' in the second, which does not necessarily mean "cannot
use `unspecified' in the 'default' face."