Attribute names when calling face-attribute

Attribute names when calling face-attribute

[fatiparty--- via Users list for the GNU Emacs text editor]

I am implementing ricci calculus notation.

Regarding the face-attribute function.  Is the attribute pre-defined or can
I select the attribute name?

For instance, could I call "(face-attribute 'default :size)" rather than
"(face-attribute 'default :height)"?
Here is my function

(defun ricci-size (size)
  "Return integer SIZE of superior and inferior glyph.
SIZE  typeface height. Integer scaled in 1/10 of point size.
Not smaller than value set by `ricci-minsize'."

  (ceiling
     (max
        (if (integerp ricci-minsize)
        ricci-minsize
      (condition-case nil ; For bootstrapping.
          (* ricci-minsize
         (face-attribute 'default :height))
        (error 0)))
    (* height ricci-scale))))  ; assumes height is integer.

Re: Attribute names when calling face-attribute

[Emanuel Berg via Users list for the GNU Emacs text editor]

fatiparty--- via Users list for the GNU Emacs text editor wrote:

> (* height ricci-scale)))) ; assumes height is integer

You can do 

  (and (integerp height) height)

to make sure it crashes on bogus data. This is better than to
have it almost always crash on bogus data ...

-- 
underground experts united
https://dataswamp.org/~incal

Attribute names when calling face-attribute

[fatiparty--- via Users list for the GNU Emacs text editor]

Jan 13, 2022, 12:54 by help-gnu-emacs@gnu.org:

> fatiparty--- via Users list for the GNU Emacs text editor wrote:
>
>> (* height ricci-scale)))) ; assumes height is integer
>>
>
> You can do 
>
>  (and (integerp height) height)
>
> to make sure it crashes on bogus data. This is better than to
> have it almost always crash on bogus data ...
>

Have changed like this, with (* glyph-size ricci-scale).  This seems to work.
I think that glyph-size should be a defined variable, rather than using "height"
as height seems to be only an attribute for the height of the font.
(defun ricci-size (glyph-size)
  "Return integer SIZE of superior and inferior glyph.
GLYPH-SIZE  Typeface height. Integer at 1/10 the point size.
Not smaller than value set by `ricci-minsize'."

  (ceiling
     (max

        (if (integerp ricci-minsize)
            ricci-minsize
          (condition-case nil ; for bootstrapping
              (* ricci-minsize (face-attribute 'default :height))
            (error 0)) )

        (* glyph-size ricci-scale)) ))  ; assumes height is integer.

I plan to allow floating point values, but that requires some thought. 

Re: Attribute names when calling face-attribute

[Emanuel Berg via Users list for the GNU Emacs text editor]

fatiparty--- via Users list for the GNU Emacs text editor wrote:

>> You can do 
>>
>>  (and (integerp height) height)
>>
>> to make sure it crashes on bogus data. This is better than to
>> have it almost always crash on bogus data ...
>
>
> Have changed like this, with (* glyph-size ricci-scale).  This seems to work.
> I think that glyph-size should be a defined variable, rather than using "height"
> as height seems to be only an attribute for the height of the font.
> (defun ricci-size (glyph-size)
>   "Return integer SIZE of superior and inferior glyph.
> GLYPH-SIZE  Typeface height. Integer at 1/10 the point size.
> Not smaller than value set by `ricci-minsize'."
>
>   (ceiling
>      (max
>
>         (if (integerp ricci-minsize)
>             ricci-minsize
>           (condition-case nil ; for bootstrapping
>               (* ricci-minsize (face-attribute 'default :height))
>             (error 0)) )
>
>         (* glyph-size ricci-scale)) ))  ; assumes height is integer.
>
> I plan to allow floating point values, but that requires some thought. 

Yuk!

What's with all the NO-BREAK SPACEs?

Remove please ...

-- 
underground experts united
https://dataswamp.org/~incal

Attribute names when calling face-attribute

[fatiparty--- via Users list for the GNU Emacs text editor]

Jan 13, 2022, 13:36 by help-gnu-emacs@gnu.org:

> fatiparty--- via Users list for the GNU Emacs text editor wrote:
>
>>> You can do 
>>>
>>>  (and (integerp height) height)
>>>
>>> to make sure it crashes on bogus data. This is better than to
>>> have it almost always crash on bogus data ...
>>>
>>
>>
>> Have changed like this, with (* glyph-size ricci-scale).  This seems to work.
>> I think that glyph-size should be a defined variable, rather than using "height"
>> as height seems to be only an attribute for the height of the font.
>> (defun ricci-size (glyph-size)
>>   "Return integer SIZE of superior and inferior glyph.
>> GLYPH-SIZE  Typeface height. Integer at 1/10 the point size.
>> Not smaller than value set by `ricci-minsize'."
>>
>>   (ceiling
>>      (max
>>
>>         (if (integerp ricci-minsize)
>>             ricci-minsize
>>           (condition-case nil ; for bootstrapping
>>               (* ricci-minsize (face-attribute 'default :height))
>>             (error 0)) )
>>
>>         (* glyph-size ricci-scale)) ))  ; assumes height is integer.
>>
>> I plan to allow floating point values, but that requires some thought. 
>>
>
> Yuk!
>
> What's with all the NO-BREAK SPACEs?
>
> Remove please ...
>
Has this to do with the email composition or the code?


> -- 
> underground experts united
> https://dataswamp.org/~incal
>

Re: Attribute names when calling face-attribute

[Emanuel Berg via Users list for the GNU Emacs text editor]

fatiparty--- via Users list for the GNU Emacs text editor wrote:

>>> (defun ricci-size (glyph-size)
>>>   "Return integer SIZE of superior and inferior glyph.
>>> GLYPH-SIZE  Typeface height. Integer at 1/10 the point size.
>>> Not smaller than value set by `ricci-minsize'."
>>>
>>>   (ceiling
>>>      (max
>>>
>>>         (if (integerp ricci-minsize)
>>>             ricci-minsize
>>>           (condition-case nil ; for bootstrapping
>>>               (* ricci-minsize (face-attribute 'default :height))
>>>             (error 0)) )
>>>
>>>         (* glyph-size ricci-scale)) ))  ; assumes height is integer.
>>>
>>> I plan to allow floating point values, but that requires some thought. 
>>>
>>
>> Yuk!
>>
>> What's with all the NO-BREAK SPACEs?
>>
>> Remove please ...
>
> Has this to do with the email composition or the code?

Since the code is part of the message here if I kill and yank
it in an Elisp buffer it is still there, and I don't have any
other source (ha) for it ... maybe it is just the e-mail for
you but that doesn't help anyone else.

Normal SPACEs will do ...

-- 
underground experts united
https://dataswamp.org/~incal

Re: Attribute names when calling face-attribute

[Eli Zaretskii]

> Date: Thu, 13 Jan 2022 01:34:53 +0100 (CET)
> From: fatiparty--- via Users list for the GNU Emacs text editor <help-gnu-emacs@gnu.org>
> 
> Regarding the face-attribute function.  Is the attribute pre-defined or can
> I select the attribute name?

They are predefined (and documented in the ELisp manual).