Le 27/09/2021 à 17:05, Andrew Zah a écrit :
Hi all,
Is it possible to do something like have lilypond evaluate a Scheme
file in order to do more complicated preprocessing of song files?
Ultimately I'd like to have a template and then include files like so,
based on some logic:
% ...
\bookpart {
\tocItem \markup "$SONG"
\include "$FILE"
% etc.
}
% ...
I know it's possible to achieve this with external tools, but I'd like
to be able to simply run `lilypond` with some flags to change the output.
Thanks,
Andrew
Hi Andrew,
What you expect is not 100% clear to me.
This file structure can be achieved with
just variables, for example included1.ly
defining
song = "LilyPond song"
and main.ly having
\tocItem \markup \song
or any kind of Scheme code:
\tocItem \markup #(string-upcase song)
To include a file of which the name is in
a variable, use
file = "/path/to/file.ly"
#(ly:parser-include-string
(string-append "\\include \"" file "\""))
To read environement variables, use Guile's
getenv function.
https://www.gnu.org/software/guile/docs/docs-1.8/guile-ref/Runtime-Environment.html#Runtime-Environment
In general, you can read parameters set from the
command line with the -e option. See
https://lilypond.org/doc/v2.22/Documentation/usage/command_002dline-usage#basic-command-line-options-for-lilypond
The typical way to construct or preprocess input would
be to define a syntax function as described at
https://lilypond.org/doc/v2.22/Documentation/extending/scheme-functions
With this approach, you're not compiling a central
.ly file anymore. You define the function in
included.ly as
myFunc =
#(define-scheme-function (...) (...)
...)
and you call it in an file you want:
\include "included.ly"
\myFunc ...
Best,
Jean
