Re: lilypond-user Digest, Vol 285, Issue 30

Hi Tina

Many thanks for these examples. They were exactly what I was looking 
for. (I'd tried something similar but got hung up over passing an entire 
score to a scheme function -- together with some inept coding errors on 
my part).

Keep up the good work !

Best regards

Roman

> Message: 1
> Date: Sat, 15 Aug 2026 20:56:32 +0200
> From: Tina Petzel <[email protected]>
> To: [email protected]
> Subject: Re: Conditionally skip an entire
> Message-ID: <[email protected]>
> Content-Type: text/plain; charset="utf-8"
>
> Hello Roman,
>
>> Hi folks
>>
>> I have a number of lilypond file which each contain several scores, call
>> the scores A, B and C.
>>
>> Depending on a variable set when invoking lilypond I need to generate
>> results which don't necessarily  contain the same scores. For instance a
>> singer might only need A and B, But an instrumentalist might need A, B
>> and C.
>>
>> Is there any way to write a condition at the top level of a lilypond
>> file (the same level as a header or a score block) to conditionally skip
>> or process an entire score.
> Absolutely. Indeed there are multiple ways to achieve this. You could simply
> wrap the scores in a `$(if ... #{ \score { ... } #})`. You can also define a
> nice function like this:
>
> %%%
> featureSet = A,B,D
>
> conditionalScore =
> #(define-scheme-function (tag score) (symbol? ly:score?)
>     (if (member tag featureSet) score))
>
> \conditionalScore A \score {
>    c'
> }
>
> \conditionalScore B \score {
>    d'
> }
>
> \conditionalScore C \score {
>    e'
> }
>
> \conditionalScore D \score {
>    f'
> }
> %%%
>
> This is just one way to do this of course, and there are many more ways to do
> this. You could also e.g. store scores in an alist and have a function that
> prints a selection of these (which would allow you to create multiple sets from
> a single file):
>
> %%%
> scores.A = \score {
>    c'
> }
>
> scores.B = \score {
>    d'
> }
>
> scores.C = \score {
>    e'
> }
>
> scores.D = \score {
>    f'
> }
>
> scoreSet =
> #(define-void-function (set) (symbol-list?)
>     (for-each
>      (lambda (sym)
>        (add-score (assoc-get sym scores)))
>      set))
>
> \book {
>    \scoreSet A,B,C,D
> }
>
> \book {
>    \scoreSet A,C,D
> }
> %%%
>
> This is particularly nice if you want to split your scores into multiple files.
> And still there are still many more ways to achieve this goal.
>
> Cheers,
> Tina