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List:       lilypond-user
Subject:    Re: Scoping problem in define-music-function
From:       Marc Hohl <marc () hohlart ! de>
Date:       2010-09-27 8:54:06
Message-ID: 4CA05BAE.9070707 () hohlart ! de
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Marc Hohl schrieb:
> Hello list,
>
> thanks to Reinhold Kainhofer and Wilbert Berendsen I managed to get a 
> callback with an
> additional argument.
>
> Now I want to write a music function like this:
>
> myFunction = #(define-music-function parser location fret music) 
> (string? ly:music?)
>  (let (( ... some expressions ... ))
>
>  #{
>     \override TabNoteHead #'stencil = #(my-special-callback fret)
>  #}
>  (..some more scheme stuff working on music...)
>  #{
>     \revert TabNoteHead #'stencil
>  #}
> ))
>
> but lilypond complains with
>
> <string>:2:46: Fehler: GUILE signalisierte einen Fehler für den hier 
> beginnenden Ausdruck
>    \override TabNoteHead #(quote stencil) = #
>                                              (my-special-callback fret)
> Unbound variable: fret
>
> So fret is not known within #{ ... #}.
Ah, I've found some $ missing. Now the error has gone away, but the 
function is still not working.

Sorry for the noise.

Marc



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