Re: cleanly dealing with variables and reducing code duplication in multimovement works

[Urs Liska]

Am 03.04.2014 08:57, schrieb Shevek:
> Hello,
>
> I'm working on a multi-movement piece, so far using a separate file for the
> score of each movement. I'm trying to add a file to the project that
> compiles all the movements and frontmatter into a single pdf, using
> bookparts, and I'm having trouble figuring out the best way to do that.

I think you should be able to do that without having to use complex 
library frameworks.

> The
> nicest way would be if all I needed to do were:
>
> \book {
>    \bookpart {
>      \include "movement1_score.ly"
>    }
>    \bookpart {
>      \include "movement2_score.ly"
>    }
> }
>
> As you might guess, that fails because each of the included files itself
> includes a file (e.g. movement1_music.ly) containing variable declarations,
> and variable declarations aren't allowed inside bookparts. The solution to
> that problem is for me to include movement1_music.ly etc. outside the \book
> block. That causes another problem, though, because I am using the same
> variable naming scheme for each of the movements. Obviously, I could solve
> that problem by adding a prefix to all the variable names, but that seems
> really yucky to me. I find myself craving some way to reference same-named
> variables in different namespaces, like movement1.flute versus
> movement2.flute.

I don't really understand what is going on here:
\book {
  music = { c }
}

seems not to be allowed either. But what works is:

musicA = { c }
musicB = { d }

music = \musicA

\bookpart {
  \music
}

music = \musicB

\bookpart {
  \music
}

From this you can create what you want together with your other question.

> Related to that craving is the fact that the score blocks for each of the
> movements are identical, which makes me feel like there ought to be some way
> to get rid of that code duplication. Really, I want to define the structure
> of the score block once, and then instantiate it multiple times, feeding
> each instance a different namespace, so that the first score block instance
> looks up "flute" in the movement1 namespace, while the second score block
> instance looks up "flute" in the movement2 namespace.

Generic description:
- Write a file that _only_ contains the score block,
  using variables with generic names (e.g. pianoUp, violin etc.)
- Ensure that these variables are present
- include the score block file

Dummy code:

\include music-1-definition.ily

\bookpart {
  \include score-block.ily
}

\include music-2-definition.ily

\bookpart {
  \include score-block.ily
}

(and leave out the \book block).

music-1-definition should create all the variables the score block expects.
music-2-definition will overwrite them so the next score block uses the 
updated variables.

HTH
Urs




> I'm sure this can't be a unique use case. Any suggestions on the best way to
> accomplish some or all of this? Am I thinking too much like a Python
> programmer to see the natural way to approach these issues in
> Lilypond/Scheme? Are some of these issues unsolvable without changes to
> Lilypond?
>
> Some similar questions:
> http://lilypond.1069038.n5.nabble.com/Books-bookparts-includes-what-td52157.html
> http://lilypond.1069038.n5.nabble.com/bookparts-with-paper-blocks-td145242.html
> http://stackoverflow.com/questions/20858042/define-function-inside-score-in-lilypond
>
> Thanks,
>
> Saul
>
>
>
> --
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