Fingering vs stem direction

[Pierre Perol-Schneider]

Hi All,

I'm looking for a function that'll do:

{
  \clef "G_8"
  \override Fingering.staff-padding = #'()
  <a-\tweak X-offset #'-.2 ^1>4
  <b-\tweak X-offset #'.2 _2>
}

As a first step, I've tried to adapt Harm's function found here: http://lilypond.1069038.n5.nabble.com/position-text-opposite-stem-direction-td51758.html#a51759

without succes:

%% After Harm:
#(define (forced-dir grob)
  (let* ((x-parent (ly:grob-parent  grob X))
         (elts (ly:grob-object x-parent 'elements))
         (grob-name (lambda (x) (assq-ref (ly:grob-property x 'meta) 'name)))
         (stems (filter (lambda (x) (eq? 'Stem (grob-name x)))
                                (ly:grob-array->list elts)))
         (stem (list-ref stems 0))
         (stem-dir (ly:grob-property stem 'direction)))

    (if (= stem-dir 1)
        (ly:grob-set-property! grob 'direction up)
        (ly:grob-set-property! grob 'direction down))))
 

{
  \clef "G_8"
  \set fingeringOrientations = #'(forced-dir)
  \override Fingering.staff-padding = #'()
  <a-1>4
  <b-2>
}

Thanks in advance for any help,

Cheers,

Pierre