Re: Scheme pattern for retrieving data in objects

[Jean Abou Samra]

Le 01/04/2022 à 18:43, Jean Abou Samra a écrit :
> \version "2.23.8"
>
> #(define-syntax-rule (fetch obj getter (sym ...) body body* ...)
>    (let ((evald-obj obj)
>          (evald-getter getter))
>      (let ((sym (getter obj 'sym))
>            ...)
>        body body* ...)))
> {
>   c'1
>   \tweak after-line-breaking
>     #(lambda (grob)
>        (fetch grob ly:grob-property (left-bound-info)
>          (fetch left-bound-info assoc-ref (common-Y X padding attach-dir)
>            (ly:message "common-Y=~a X=~a padding=~a attach-dir=~a" 
> common-Y X padding attach-dir))))
>   \startTextSpan
>   c'1\stopTextSpan
> }

Sorry, should have been:

\version "2.23.8"

#(define-syntax-rule (fetch obj getter (sym ...) body body* ...)
   (let ((evald-obj obj)
         (evald-getter getter))
     (let ((sym (evald-getter evald-obj 'sym))
           ...)
       body body* ...)))
{
  c'1
  \tweak after-line-breaking
    #(lambda (grob)
       (fetch grob ly:grob-property (left-bound-info)
         (fetch left-bound-info assoc-ref (common-Y X padding attach-dir)
           (ly:message "common-Y=~a X=~a padding=~a attach-dir=~a" 
common-Y X padding attach-dir))))
  \startTextSpan
  c'1\stopTextSpan
}