Repeat commands grace echo purger - Revision history

Lemzwerg: Snippet is broken

2025-12-27T20:59:58Z

Snippet is broken

← Older revision		Revision as of 20:59, 27 December 2025
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			<div style="color: red">This is currently broken, not working with 2.24 or newer.</div>

	One subtype of the '''''grace synchronization issue''''' is the '''''grace echo'''''. It occurs if one voice sends an (system wide collected) event (e.g. start of repeat, start or end of volta) before a grace note, while another voice does it after this grace note (usually because there is no grace note in the other voice). Then simply ''ignoring'' the second occurrence after the grace notes is a quick help.<br />		One subtype of the '''''grace synchronization issue''''' is the '''''grace echo'''''. It occurs if one voice sends an (system wide collected) event (e.g. start of repeat, start or end of volta) before a grace note, while another voice does it after this grace note (usually because there is no grace note in the other voice). Then simply ''ignoring'' the second occurrence after the grace notes is a quick help.<br />
	Off course, it cannot help if there is no event before the first grace note at all, e.g. if you use a parallel control voice without grace notes to define the repeat structure.<br />		Off course, it cannot help if there is no event before the first grace note at all, e.g. if you use a parallel control voice without grace notes to define the repeat structure.<br />
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	[[Category:Contexts and engravers]]		[[Category:Contexts and engravers]]
			[[Category:Correction wanted]]
	[[Category:Repeats]]		[[Category:Repeats]]
	~~[[Category:Contexts and engravers]]~~
	[[Category:Workaround]]		[[Category:Workaround]]
	[[Category:Snippet]]		[[Category:Snippet]]

Lemzwerg: New category

2025-11-21T23:23:01Z

New category

← Older revision		Revision as of 23:23, 21 November 2025
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	[[Category:Repeats]]		[[Category:Repeats]]
	[[Category:Contexts and engravers]]		[[Category:Contexts and engravers]]
	[[Category:Workaround]][[Category:Snippet]]		[[Category:Workaround]]
			[[Category:Snippet]]

Lemzwerg at 22:58, 21 November 2025

2025-11-21T22:58:56Z

← Older revision		Revision as of 22:58, 21 November 2025
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	[[Category:Repeats]]		[[Category:Repeats]]
	[[Category:Contexts and engravers]]		[[Category:Contexts and engravers]]
	[[Category:Workaround]]		[[Category:Workaround]][[Category:Snippet]]

Jean Abou Samra: Replace version="2.24.0" with version="2.24" now that the LilyWiki extension supports auto-selecting the latest release in a stable series

2025-11-16T18:56:29Z

Replace version="2.24.0" with version="2.24" now that the LilyWiki extension supports auto-selecting the latest release in a stable series

← Older revision		Revision as of 18:56, 16 November 2025
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	With the '''''\repeat''''' and '''''\alternative''''' commands this method is a little tricky, because it must be done within an exact sequence of the other engravers. This example illustrates how it's done '''directly''' by context modifications and using a scheme engraver, and this source code also describes how it will be implemented by patching your LILYPOND installation.		With the '''''\repeat''''' and '''''\alternative''''' commands this method is a little tricky, because it must be done within an exact sequence of the other engravers. This example illustrates how it's done '''directly''' by context modifications and using a scheme engraver, and this source code also describes how it will be implemented by patching your LILYPOND installation.

	<lilypond version="2.24.0">		<lilypond version="2.24">
	%by: ArnoldTheresius		%by: ArnoldTheresius

Jean Abou Samra: Import snippet from LSR

2025-10-26T22:49:29Z

Import snippet from LSR

New page

One subtype of the '''''grace synchronization issue''''' is the '''''grace echo'''''. It occurs if one voice sends an (system wide collected) event (e.g. start of repeat, start or end of volta) before a grace note, while another voice does it after this grace note (usually because there is no grace note in the other voice). Then simply ''ignoring'' the second occurrence after the grace notes is a quick help.<br />
Off course, it cannot help if there is no event before the first grace note at all, e.g. if you use a parallel control voice without grace notes to define the repeat structure.<br />
With the '''''\repeat''''' and '''''\alternative''''' commands this method is a little tricky, because it must be done within an exact sequence of the other engravers. This example illustrates how it's done '''directly''' by context modifications and using a scheme engraver, and this source code also describes how it will be implemented by patching your LILYPOND installation.

<lilypond version="2.24.0">
%by: ArnoldTheresius

#(define-public (Local_repeatcommands_graceecho_purger ctx)
(let ((last-main-moment -1)
(accumulated-repeat-list '()))
(make-engraver
((process-music trans)
(let*
((now-mom (ly:context-current-moment ctx))
(now-main-mom (ly:moment-main now-mom))
(current-repeat-list (ly:context-property ctx 'repeatCommands)))
(if (not (equal? last-main-moment now-main-mom))
(set! accumulated-repeat-list '()))
(if (not (null? current-repeat-list))
(let ((new-repeat-list '()))
(for-each
(lambda (x)
(let ((tokken x))
(if (pair? x) ;;; only volta expected!
(if (and (boolean? (cadr x)) (eq? (cadr x) #f))
(set! tokken 'volta--end)
(set! tokken 'volta--start)))
(if (not (memq tokken accumulated-repeat-list))
(begin
(set! new-repeat-list (cons x new-repeat-list))
(set! accumulated-repeat-list
(cons tokken accumulated-repeat-list))))))
current-repeat-list)
(ly:context-set-property!
ctx 'repeatCommands
(reverse! new-repeat-list))))
(set! last-main-moment now-main-mom))))))

Music = {
\tag #'Grace \acciaccatura b8 c'1
\inStaffSegno
\repeat volta 2 {
\tag #'Grace \acciaccatura b8 c'1
}
\alternative {
{
\tag #'Grace \acciaccatura b8 c'1
} {
\tag #'Grace \acciaccatura b8 c'1
}
}
\tag #'Grace \acciaccatura b8 c'1
}

\score {
\new StaffGroup <<
\new Staff {
\Music
}
\new Staff {
\removeWithTag #'Grace \Music
}
>>
\layout {
\context { \Score
\remove "Repeat_acknowledge_engraver"
\remove "Volta_engraver"
% this scheme engraver defined above must be placed
% before the 'Repeat_acknowledge_engraver', and all
% dependent engravers (i.e. the "Volta_engraver")
% must follow.
% As there is no »before engraver xxx« option in
% the '\consists' command, I did remove both before
% I added the new scheme engraver, then I added
% the two engravers again.
\consists #Local_repeatcommands_graceecho_purger
\consists "Repeat_acknowledge_engraver"
\consists "Volta_engraver"

%%% I have already patched my LILYPOND as listed below!
%%% This is the syntax how to disable this patch in a \score block
% \remove #Repeatcommands_graceecho_purger
}
}
}

\score {
\new Staff { e'1 \inStaffSegno e' \inStaffSegno \repeat volta 2 { e' } }
}

\markup \wordwrap {
If you want to use it in every compilation, you may patch your LILYPOND installation:
Follow the instruction you'll find here in the source code.
}
%{
PATCH INSTRUCTION:

1. locate the file
.../usr/share/lilypond/current/scm/music-functions.scm
and append these 27 lines:
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Extension for grace echo purging
(define-public (Repeatcommands_graceecho_purger ctx)
(let ((last-main-moment -1)
(accumulated-repeat-list '()))
(make-engraver
((process-music trans)
(let*
((now-mom (ly:context-current-moment ctx))
(now-main-mom (ly:moment-main now-mom))
(current-repeat-list (ly:context-property ctx 'repeatCommands)))
(if (not (equal? last-main-moment now-main-mom))
(set! accumulated-repeat-list '()))
(if (not (null? current-repeat-list))
(let ((new-repeat-list '()))
(for-each (lambda (x)
(let ((tokken x))
(if (pair? x) ;;; only volta expected!
(if (and (boolean? (cadr x)) (eq? (cadr x) #f))
(set! tokken 'volta--end)
(set! tokken 'volta--start)))
(if (not (memq tokken accumulated-repeat-list)) (begin
(set! new-repeat-list (cons x new-repeat-list))
(set! accumulated-repeat-list (cons tokken accumulated-repeat-list)))))
) current-repeat-list)
(ly:context-set-property! ctx 'repeatCommands (reverse! new-repeat-list))))
(set! last-main-moment now-main-mom))))))

2. locate the file
.../usr/share/lilypond/current/ly/engraver-init.ly,
open it with an text editor,
find the line containing
\consists "Repeat_acknowledge_engraver"
and add just _b_e_f_o_r_e_ this the line
\consists #Repeatcommands_graceecho_purger

%}
</lilypond>

[[Category:Contexts and engravers]]
[[Category:Repeats]]
[[Category:Contexts and engravers]]
[[Category:Workaround]]