Am 19.07.2017 um 10:43 schrieb David Kastrup: > Urs Liska <u...@openlilylib.org> writes: > >> Obviously I didn't make myself clear enough and probably I should have >> invested the time for a minimal example. When sloppily using the word >> "override" I didn't mean "\override" but applying a value to a grob >> property in a grob callback function. >> >> I have a data structure idTweaks, currently using an alist: >> >> idTweaks = #'() >> >> This alist gets populated with elements consisting of a key and a >> #'(property . value) pair with >> >> idTweak = >> #(define-void-function (id prop val)(string? symbol? scheme?) >> (set! idTweaks (assoc-set! idTweaks id (cons prop val)))) >> >> using commands like >> >> \idTweak "id-1" color #red >> \idTweak "id-2" extra-offset #'(2 . -2) > You are aware that > > idTweaks.id-1.color = #red > idTweaks.id-2.extra-offset = #'(2 . -2) > > would have done the same?
No! (but only if id-1 were a symbol, right? >> In the callback stage the callback function looks up if a grob has an >> 'id property and if there's a matching entry in idTweaks: >> >> #(define (apply-tweaks grob) >> (let* >> ((id (ly:grob-property grob 'id)) >> (tweak (if (null? id) >> #f >> (assoc-ref idTweaks id)))) >> (if tweak >> (ly:grob-set-property! grob (car tweak) (cdr tweak))))) > At any rate: yes it would make sense to use a hashtable here. OK, good to know (and be confirmed). > It would > also make a lot of sense to use 'id-1 (namely a symbol) rather than > "id-1" for lookup since symbols are much easier and faster to compare > for equality than strings are (and can be compared using eq? rather than > equal?). In fact in my real example I *do* change the typecheck of the id property to use symbols, but I didn't want to complicate the minimal example :-) > I wouldn't tamper with the alist-based property handling of > grobs though. I didn't think about such a thing. Best Urs -- u...@openlilylib.org https://openlilylib.org http://lilypondblog.org _______________________________________________ lilypond-user mailing list lilypond-user@gnu.org https://lists.gnu.org/mailman/listinfo/lilypond-user
