12.1.2 Simple substitution functions

Here is a simple example,

     
     padText = #(define-music-function (parser location padding) (number?)
       #{
         \once \override TextScript #'padding = #$padding
       #})
     
     \relative c''' {
       c4^"piu mosso" b a b
       \padText #1.8
       c4^"piu mosso" d e f
       \padText #2.6
       c4^"piu mosso" fis a g
     }

Music expressions may be substituted as well,

     
     custosNote = #(define-music-function (parser location note)
                                          (ly:music?)
       #{
         \once \override Voice.NoteHead #'stencil =
           #ly:text-interface::print
         \once \override Voice.NoteHead #'text =
           \markup \musicglyph #"custodes.mensural.u0"
         \once \override Voice.Stem #'stencil = ##f
         $note
       #})
     
     { c' d' e' f' \custosNote g' }

Multiple variables may be used,

     
     tempoMark = #(define-music-function (parser location padding marktext)
                                         (number? string?)
     #{
       \once \override Score . RehearsalMark #'padding = $padding
       \once \override Score . RehearsalMark #'no-spacing-rods = ##t
       \mark \markup { \bold $marktext }
     #})
     
     \relative c'' {
     c2 e
     \tempoMark #3.0 #"Allegro"
     g c
     }