tuplet numbers on kneed beams - David's function stopped working

[Janek Warchoł]

Hi,

David Nalesnik's function correcting tuplet number placement on kneed
beams throws an error with Lilypond 2.17.5 (it works with 2.16.0):

Drawing systems.../home/janek/desk/tuplet_numers_on_kneed_beams.ily:44:26:
In procedure * in expression (* 0.5 (ly:grob-property beam #)):
/home/janek/desk/tuplet_numers_on_kneed_beams.ily:44:26: Wrong type: ()

line 44 reads:
(beam-gap (* 0.5 (ly:grob-property beam 'gap)))

i have no idea why this doesn't work.  I had looked for commits that
said something about gaps, but hadn't find anything.  Maybe it's
related to some commits about grob-properties:

6d70f060737dabc13c3fce1ec811f534ca94e585
Author: David Kastrup <address@hidden>
Date:   Mon Sep 24 11:59:42 2012 +0200

    Issue 2856: Get along with use of grob-property instead of
grob-property-path in overrides

or

dda8739f019fad832b2c59aa5675a42717c15637
Author: Keith OHara <address@hidden>
Date:   Wed Aug 29 12:47:47 2012 -0700

    grob-property.cc: outdated comment

?

David's function is in the attachment.

best,
Janek

tuplet_numers_on_kneed_beams.ily
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