Hello anyone on the bug list, could someone just verify what was
reported by Paul (below) sounds correct and if this is a bug or just a
doc edit (or both).
Thanks,
James
Thanks for reminding.
Le 25/08/2021 à 15:36, Paul Hodges a écrit :
On the page:
http://lilypond.org/doc/v2.23/Documentation/notation/custom-titles-headers-and-footers
the syntax for using \on-the-fly is specified as:
variable = \markup {
…
\on-the-fly \procedure markup
…
}
and the following examples use the same. Note the use of \ to introduce
the procedure.
However, this does not work for all procedures - specifically not in the
case of \(on-page n). But using # instead of \ works in all cases, and
is also more logical as introducing the parameter for \on-the-fly.
Yeah, the documentation is weird here. Basically,
\ looks up a LilyPond variable. Since LilyPond and
its Scheme interpreter are very closely tied, Scheme
variables are available to LilyPond and vice-versa
(in fact they are stored exactly the same; just that
a variable called abc123xyz$^ will be accessible to
Scheme but not to LilyPond due to syntax restrictions).
In contrast, # starts a chunk of Scheme code, so it
is another way to access the variable. But
(procedure argument1 argument2 ...)
is Scheme syntax. So it only works with #.
It would seem logical to change the documentation to specify and use #
instead of \ for these procedures.
Well, the implementation is also very weird here.
Perhaps an artifact of earlier design. I am pretty
sure there is no need for \on-the-fly whatsoever;
one could just implement it with the syntax
\if \first-page blablabla
\if \not \first-page blablabla
\if \on-page #5 blablabla
\if \not \single-page blablabla
etc.
I'll probably propose a patch.
Best,
Jean
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