[PATCH] memq mistake in NR 6.5.2?

[Mark Polesky]

>From NR 6.5.2 Running a function on all layout objects:

#(define (blanker grob grob-origin context)
 (if (and (memq (ly:grob-property grob 'interfaces)
                note-head-interface)
          (eq? (ly:grob-property grob 'staff-position) 0))
     (set! (ly:grob-property grob 'transparent) #t)))

But to get it to work, I had to change lines 2-3 to:

 (if (and (memq 'note-head-interface (ly:grob-interfaces grob))

     
Also, the syntax is given as: \applyOutput context proc
but it would be nice to know that CONTEXT needs a hash-quote
(#'). Perhaps a tiny example work be enough:

@lilypond[quote,verbatim,ragged-right]
#(define (blanker grob grob-origin context)
   (if (and (memq 'note-head-interface (ly:grob-interfaces grob))
            (eq? (ly:grob-property grob 'staff-position) 0))
       (set! (ly:grob-property grob 'transparent) #t)))

\relative {
  e4 g8 \applyOutput #'Voice #blanker b d2
}
@end lilypond

If it's a simple as that, the patch I've included should work.
- Mark

0001-NR-6.5.2-Correct-and-clarify-applyOutput-example.patch
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