Re: defface/defcustom question

[Simon Josefsson <jas@extundo.com>]

kai.grossjohann@gmx.net (Kai Großjohann) writes:

> Simon Josefsson <jas@extundo.com> writes:
>
>> kai.grossjohann@gmx.net (Kai Großjohann) writes:
>>
>>> Simon Josefsson <jas@extundo.com> writes:
>>>
>>>> It also makes it possible to express "use the same face for this, that
>>>> and this" and then later be able to change the face only once to
>>>> change it in all places.
>>>
>>> But that's possible with regular faces already?  Just use the same
>>> symbol (face name) in all those places?
>>
>> You mean changing gnus source?  I meant for users.
>
> I don't understand.  The default font-lock setup is to use different
> faces for all the elements in the server buffer.  If you want to
> change the look of the faces, set-face-foreground and friends seem to
> be sufficient.
>
> Obviously, they can be used to make different faces look the same.
>
> And equally obviously, if font-lock-keywords specifies the same face
> for construct A and B, then they will always look the same,
> regardless of whether a variable is used or a face is used
> directly -- a variable can only have one value after all...
>
> I think I'm misunderstanding you completely; I hope the above helps
> to show you what my weak mind is thinking so that you can guide me
> out of the fog.  I apologize for being so dense :-/

You are right in all that, and I wasn't clear.  Consider a user that
customizes some face to RED, and then wants the server buffer to use
that face for everything.  She can then customize all the server
buffers to have a RED face.  But, the point of having a variable would
be if the user then changes her mind on the original RED face, and
wants it to be BLUE.  Initially, instead of changing the faces, she
would only have changed the server buffer face names to point at the
original RED face name.  So if she changes the original RED face to
BLUE, then all server buffer faces also changes to BLUE.

Now it seems customize-face supports inheritance, so this can be
achieved anyway, but perhaps that feature didn't exist when the face
name idea was implemented.

So I don't know what the real reason for still supporting face names
is.  Backwards compatibility?  Does XEmacs support face inheritance?
Maybe we should ask on emacs-devel, if nobody else here knows, since
several other parts of Emacs also uses face names.