On 2021-06-29 1:20 pm, David Kastrup wrote:
%%%%
\version "2.22.0"
SvgAddClassName =
#(lambda (ctxt)
(define (add-class-name grob)
(let* ((attribs (ly:grob-property grob 'output-attributes '()))
(class (ly:assoc-get 'class attribs '()))
(name (grob::name grob)))
(set! class (if (null? class) name (format #f "~a ~a" class
name)))
(set! attribs (assoc-set! attribs 'class class))
(ly:grob-set-property! grob 'output-attributes attribs)))
(make-engraver
(acknowledgers
((grob-interface engraver grob source)
(add-class-name grob)))))
That assoc-set! looks like a stinker. Doesn't it mess with shared data
structures?
Hrm... would it be better to explicitly alist-copy the result from
ly:assoc-get? Actually, I guess you could do:
;;;;
(alist-cons 'class ... (alist-delete 'class attribs))
;;;;
...since the SRFI says that alist-delete does not modify the original
structure, only that it might return an alist with a common tail.
And on this point, should LilyPond provide an ly:assoc-set to pair with
ly:assoc-get that avoids potential issues with shared structures?
-- Aaron Hill
