Re: Solution for including a file only once

[Carl Sorensen]

On 2/11/10 11:05 AM, "Michael J. O'Donnell" <address@hidden>
wrote:

> Here's what I *now think* is correct code O:-) :
> 
> includeIfAbsent =
> 
> #(define-music-function (parser location fileName) (string?)
> 
> (let ((guardName (string-append "Already Got " fileName)))
> 
> (if (not (defined? (string->symbol guardName)))
> (begin
> 
> (primitive-eval (list 'define (string->symbol guardName) #t))
> 
> (ly:parser-parse-string (ly:parser-clone parser) (string-concatenate
> (list "\\include \"" fileName "\"")))
> 
> #{ #}

When I see #{ #}, I suspect that instead of using the substitution syntax,
you should be using void  music functions (i.e. your return should be
(make-music 'SequentialMusic 'void #t)).  This is the empty music you refer
to below.

You can read more about void music functions in Notation Reference 6.1.5 for
version 2.12 or in Extending LilyPond 2.1.5 for version 2.13.

Thanks,

Carl