Filtering parts from the command line
If you need to create scores for different audiences from the same sources you need to filter the input. The \tag command partially addresses this, but source files have to be changed in order to create different scores. This snippet shows how to use scheme code to filter music expressions, markup expressions, set up header fields and layout context overrides based on a switch passed on the command line.
The basic idea is to use a command line such as lilypond -dtarget=chords -o chords snippet.ly, for example, to build a score emphasizing chords. In the input file several facilities are provided:
- Music expressions are filtered using the construct
\ifTargetIn #'(<list of eligible targets>) expr. If the target entered on the command-line isn't in the list, then the expression won't be rendered. - Markup expressions are filtered using the similar construct
\if-target-in #'(<list of eligible targets>) expr. - The macro
\targetNameis provided and can be assigned to header fields. This name isn't the actual text of the target but can be more exotic, for example'chords => "Full accompaniment". You just need to set up the the target-names map correctly. - Context properties need to be set in some cases, for instance in order reduce the size of a score to get it on a single page. Luckily Lilypond allows this using a construct like
\override LyricText #'font-size = #(value-if-target-in '(chords) -1 0).
\version "2.24.0"
%% http://lsr.di.unimi.it/LSR/Item?id=493
%%
%% Based on the ideas, work, hard slog and implementations of Nicolas Sceaux,
%% (who also had to do the reviews.)
%%
%% current-target
%% Target option passed on the command line. If none found, then use the
%% target 'default
%%
#(define current-target (or (ly:get-option 'target) 'default))
%%
%% set-target!
%% Utility routine to override the current target. Specifically used in
%% this snippet to simulate different passes over the input files.
%% target symbol New target (as if it had been set by -dtarget=
%%
#(define (set-target! target)
(set! current-target target))
%%
%% value-if-target-in
%% Utility routine to set a value depending on whether the candidate
%% list contains the current-target.
%% eligible list List of symbols
%% value Value to return if the eligible list contains
%% the current target.
%% else-value Value to return if the current target isn't in
%% the list of eligible.
%%
#(define (value-if-target-in eligible value else-value)
(if (memq current-target eligible)
value
else-value))
%%
%% target-names
%% Map of target names
%%
#(define target-names
'((chords ."With explicit chords")
(song ."With all lyrics")))
%%
%% Set up an instrument name for the header
%%
targetName = #(assoc-ref target-names current-target)
%%
%% ifTargetIn
%% Render the music expression if the target is in the eligible list
%%
ifTargetIn =
#(define-music-function (eligible music)
(list? ly:music?)
(value-if-target-in eligible music (make-music 'Music)))
%%
%% if-target-in
%% Render the markup expression if the target is in the eligible list
%%
#(define-markup-command (if-target-in layout props eligible markp)
(list? markup?)
(value-if-target-in eligible
(interpret-markup layout props markp)
empty-stencil))
%%% SNIPPET SPECIFIC WORKAROUND SECTION =================================
%%% THIS IS NOT PART OF THE EXAMPLE CODE -- JUST A WORKAROUND.
%%% As we fake the "-d target=xxx" command line switch by setting the
%%% target option in the source file itself, and as when markup commands
%%% are interpreted the whole file as been read long ago, the
%%% \if-target-in markup command sees that the selected target option is
%%% the last one set using set-target!
%%% In practice, the option would be set once, from the command line switch.
%%% But here, as we fake in a single file the three possible calls, we use
%%% this music function as a workaround.
toplevelMarkupIfTargets =
#(define-music-function (eligible text)
(list? markup?)
(if (memq current-target eligible)
(collect-scores-for-book
(if (>= (cadr (ly:version)) 11)
(list text)
text)))
(make-music 'Music 'void #t))
%%% Redefine this as a no-op to still be able to use it in the examples
#(define-markup-command (if-target-in layout props eligible markp)
(list? markup?)
(interpret-markup layout props markp))
%%% END SNIPPET SPECIFIC WORKAROUND SECTION =============================
%% ======================================================================
txtChorus = \lyricmode {
\set stanza = "Ch." This is a ve- ry me- lo- dious cho- rus.
}
txtVerseI = \lyricmode {
\set stanza = "1." And this is the first verse of three. This
}
txtVerseII = \lyricmode {
\set stanza = "2." And now this is the se- cond one.
}
txtVerseIII = \lyricmode {
\set stanza = "3." And this is the end of my song.
}
mlChorus = \markup { C. \italic { This is a very melodious chorus. } }
mlVerseI = \markup { 1. And this is the first verse of three. }
mlVerseII = \markup { 2. And now this is the second one. }
mlVerseIII = \markup { 3. And this is the end of my song.}
chdBoth = \chordmode { c4 g1 c g c }
treChorusI = \relative c'' { g4 | a2 b4 c8 c16 d32 e | f2 e4 d | }
treVerseI = \relative c'' { g4. a8 b4. c8 | g4 a8 b c b\rest g4 | }
treBothII = \relative c' {
s4 | e2 e2 | d8 e d e d e d e | d8 e d e d e d e | d8 e d e d s s4 |
}
basBothI = \relative c' {
c4 | b2 c2 | d2 c2 | b2 c2 | d2 c8 d,\rest c'4 |
}
basBothII = \relative c {
c16 c c c | d16 e d e d e d e d e d e d e d e |
d16 e d e d e d e d e d e d e d e |
d16 e d e d e d e d e d e d e d e |
d16 e d e d e d e d e s8 c16 c c c |
}
global = {
\key c \major
\time 4/4
\partial 4 s4 s1*2 \bar "||"
s1*2 \bar "|."
}
%% ======================================================================
%% FIRST PASS : Score with default target
%% Simulate the command > lilypond <filename>
\markup \box \line \typewriter { > lilypond <filename> }
targetName = #(assoc-ref target-names current-target)
%% ======================================================================
\score {
\context ChoirStaff <<
\ifTargetIn #'(orgue default) \new ChordNames { \chdBoth }
\new Staff <<
\global \clef treble
{
\new Voice = "chorus" {
\ifTargetIn #'(default) \voiceOne
\treChorusI
}
\break
\new Voice = "verse" {
\ifTargetIn #'(default) \voiceOne
\treVerseI
}
}
\\ \ifTargetIn #'(default) { \voiceTwo \treBothII }
>>
\new Lyrics \lyricsto "chorus" \txtChorus
\new Lyrics \lyricsto "verse" \txtVerseI
% The following dummy line has been added to the original snippet for compatibility
% with 2.14 and 2.15. You may be able to remove it in other versions.
#(begin)
\ifTargetIn #'(song) <<
\new Lyrics \lyricsto "verse" \txtVerseII
\new Lyrics \lyricsto "verse" \txtVerseIII
>>
\ifTargetIn #'(default) \new Staff <<
\global \clef bass
\basBothI \\ \basBothII
>>
\ifTargetIn #'(chords) \new Staff <<
\global \clef bass
\transpose c c, \chdBoth
>>
>>
\header { piece = \targetName }
\layout {
\context { \Lyrics
\override LyricText.font-shape = #(value-if-target-in '(chords) 'italic 'upright)
}
}
}
\toplevelMarkupIfTargets #'(default) % WORKAROUND - ignore this line
\markup \if-target-in #'(default) \fill-line {
\column{
\line{\pad-around #1.5 {\mlChorus}}
\line{\pad-around #1.5 {\mlVerseI}}
\line{\pad-around #1.5 {\mlVerseII}}
\line{\pad-around #1.5 {\mlVerseIII}}
}
}
%% ======================================================================
%% SECOND PASS : Score with `chords' target
%% Simulate the command > lilypond -dtarget=chords -o chords <filename>
#(set-target! 'chords)
\markup \box \line \typewriter { > lilypond -dtarget=chords -o chords <filename> }
targetName = #(assoc-ref target-names current-target)
%% ======================================================================
%\noPageBreak
\score {
\context ChoirStaff <<
\ifTargetIn #'(chords default) \new ChordNames { \chdBoth }
\new Staff <<
\global \clef treble
{
\new Voice = "chorus" {
\ifTargetIn #'(default) \voiceOne
\treChorusI
}
\break
\new Voice = "verse" {
\ifTargetIn #'(default) \voiceOne
\treVerseI
}
}
\\ \ifTargetIn #'(default) { \voiceTwo \treBothII }
>>
\new Lyrics \lyricsto "chorus" \txtChorus
\new Lyrics \lyricsto "verse" \txtVerseI
#(begin) % see comment above
\ifTargetIn #'(song) <<
\new Lyrics \lyricsto "verse" \txtVerseII
\new Lyrics \lyricsto "verse" \txtVerseIII
>>
\ifTargetIn #'(default) \new Staff <<
\global \clef bass
\basBothI \\ \basBothII
>>
\ifTargetIn #'(chords) \new Staff <<
\global \clef bass
\transpose c c, \chdBoth
>>
>>
\header { piece = \targetName }
\layout {
\context { \Lyrics
\override LyricText.font-shape = #(value-if-target-in '(chords) 'italic 'upright)
}
}
}
\toplevelMarkupIfTargets #'(default) % WORKAROUND - ignore this line
\markup \if-target-in #'(default) \fill-line {
\column{
\line{\pad-around #1.5 {\mlChorus}}
\line{\pad-around #1.5 {\mlVerseI}}
\line{\pad-around #1.5 {\mlVerseII}}
\line{\pad-around #1.5 {\mlVerseIII}}
}
}
%% ======================================================================
%% THIRD PASS : Score with `song' target
%% Simulate the command > lilypond -dtarget=song -o song <filename>
#(set-target! 'song)
\markup \box \line \typewriter { > lilypond -dtarget=song -o song <filename> }
targetName = #(assoc-ref target-names current-target)
%% ======================================================================
%\noPageBreak
\score {
\context ChoirStaff <<
\ifTargetIn #'(chords default) \new ChordNames { \chdBoth }
\new Staff <<
\global \clef treble
{
\new Voice = "chorus" {
\ifTargetIn #'(default) \voiceOne
\treChorusI
}
\break
\new Voice = "verse" {
\ifTargetIn #'(default) \voiceOne
\treVerseI
}
}
\\ \ifTargetIn #'(default) { \voiceTwo \treBothII }
>>
\new Lyrics \lyricsto "chorus" \txtChorus
\new Lyrics \lyricsto "verse" \txtVerseI
#(begin) % see comment above
\ifTargetIn #'(song) <<
\new Lyrics \lyricsto "verse" \txtVerseII
\new Lyrics \lyricsto "verse" \txtVerseIII
>>
\ifTargetIn #'(default) \new Staff <<
\global \clef bass
\basBothI \\ \basBothII
>>
\ifTargetIn #'(chords) \new Staff <<
\global \clef bass
\transpose c c, \chdBoth
>>
>>
\header { piece = \targetName }
\layout {
\context { \Lyrics
\override LyricText.font-shape = #(value-if-target-in '(chords) 'italic 'upright)
}
}
}
\toplevelMarkupIfTargets #'(default) % WORKAROUND - ignore this line
\markup \if-target-in #'(default) \fill-line {
\column{
\line{\pad-around #1.5 {\mlChorus}}
\line{\pad-around #1.5 {\mlVerseI}}
\line{\pad-around #1.5 {\mlVerseII}}
\line{\pad-around #1.5 {\mlVerseIII}}
}
}
