Re: Function for /score block

[Aaron Hill]

On 2019-04-24 10:01 pm, foxfanfare wrote:
> [ . . . ] The only thing
> that might change is the name of the piece (here it is "IA"). I wonder, 
> is
> it possible, instead of copying each time the same instrumentation, to 
> call
> this block in a function and replace each time the name of the piece by 
> the
> one defined? For instance, something like "\instrumentation #"IA"" or
> "\instrumentation #"IB"", etc...

I had to typeset some hymns for projection recently and wanted a way to 
reduce the amount of typing when it came to scores and books that were 
basically the same structurally.  (In my case, I was using a void 
function and calling print-book-with-defaults since I was constructing a 
\book, not the body of a \score.)

I found using ly:parser-include-string was helpful for this purpose.  
Consider the following:

%%%%
\version "2.19.82"

Alice.Melody = \fixed f' { f4 g a bes c'1 }
Alice.Lyrics = \lyricmode { do re mi fa sol }

Bob.Melody = \fixed f' { c'4 bes d' g a1 }
Bob.Lyrics = \lyricmode { sol fa la re mi }

Global = {
  \key f \major
  s1*2 \bar "|."
}

makeItSo = #(define-music-function (label) (symbol?)
  (define (lookup section) (ly:parser-include-string
    (format #f "\\~a.~a" label section)))
  #{ <<
       \new Staff \with {
         instrumentName = $(symbol->string label)
       } <<
         \Global
         \new Voice = "melody" { $(lookup 'Melody) }
       >>
       \new Lyrics \lyricsto "melody" { $(lookup 'Lyrics) }
     >> #} )

\makeItSo #'Alice
\makeItSo #'Bob
%%%%

This \makeItSo is akin to a macro, able to inject a dynamically 
constructed string into the parser as if it were typed by hand.

-- Aaron Hill