Refactor get/set_property to take the item as first argument

lily/flag.cc

 /*
   This file is part of LilyPond, the GNU music typesetter.
 
   Copyright (C) 1996--2020 Han-Wen Nienhuys <hanwen@xs4all.nl>
   Jan Nieuwenhuizen <janneke@gnu.org>
 
   LilyPond is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.
@@ skipping 31 matching lines @@
   DECLARE_SCHEME_CALLBACK (calc_x_offset, (SCM));
 
   static SCM internal_calc_y_offset (SCM smob, bool pure);
 };
 
 MAKE_SCHEME_CALLBACK (Flag, width, 1);
 SCM
 Flag::width (SCM smob)
 {
   Grob *me = unsmob<Grob> (smob);
-  Stencil *sten = unsmob<Stencil> (me->get_property ("stencil"));
+  Stencil *sten = unsmob<Stencil> (get_property (me, "stencil"));
   if (!sten)
     return ly_interval2scm (Interval (0.0, 0.0));
 
   Grob *stem = me->get_parent (X_AXIS);
 
   /*
     TODO:
     This reproduces a bad hard-coding that has been in the code for quite some time:
     the bounding boxes for the flags are slightly off and need to be fixed.
   */
 
   return ly_interval2scm (sten->extent (X_AXIS) - stem->extent (stem, X_AXIS)[RIGHT]);
 }
 
 MAKE_SCHEME_CALLBACK (Flag, glyph_name, 1);
 SCM
 Flag::glyph_name (SCM smob)
 {
   Grob *me = unsmob<Grob> (smob);
   Grob *stem = me->get_parent (X_AXIS);
 
   Direction d = get_grob_direction (stem);
   int log = Stem::duration_log (stem);
   string flag_style;
 
-  SCM flag_style_scm = me->get_property ("style");
+  SCM flag_style_scm = get_property (me, "style");
   if (scm_is_symbol (flag_style_scm))
     flag_style = ly_symbol2string (flag_style_scm);
 
   bool adjust = true;
 
   string staffline_offs;
   if (flag_style == "mensural")
     /* Mensural notation: For notes on staff lines, use different
        flags than for notes between staff lines.  The idea is that
        flags are always vertically aligned with the staff lines,
@@ skipping 23 matching lines @@
 MAKE_SCHEME_CALLBACK (Flag, print, 1);
 SCM
 Flag::print (SCM smob)
 {
   Grob *me = unsmob<Grob> (smob);
   Grob *stem = me->get_parent (X_AXIS);
 
   Direction d = get_grob_direction (stem);
   string flag_style;
 
-  SCM flag_style_scm = me->get_property ("style");
+  SCM flag_style_scm = get_property (me, "style");
   if (scm_is_symbol (flag_style_scm))
     flag_style = ly_symbol2string (flag_style_scm);
 
   if (flag_style == "no-flag")
     return Stencil ().smobbed_copy ();
 
   char dir = (d == UP) ? 'u' : 'd';
   Font_metric *fm = Font_interface::get_default_font (me);
-  string font_char = robust_scm2string (me->get_property ("glyph-name"), "");
+  string font_char = robust_scm2string (get_property (me, "glyph-name"), "");
   Stencil flag = fm->find_by_name (font_char);
   if (flag.is_empty ())
     me->warning (_f ("flag `%s' not found", font_char));
 
   /*
     TODO: maybe property stroke-style should take different values,
     e.g. "" (i.e. no stroke), "single" and "double" (currently, it's
     '() or "grace").  */
-  SCM stroke_style_scm = me->get_property ("stroke-style");
+  SCM stroke_style_scm = get_property (me, "stroke-style");
   if (scm_is_string (stroke_style_scm))
     {
       string stroke_style = ly_scm2string (stroke_style_scm);
       if (!stroke_style.empty ())
         {
           string font_char = flag_style + dir + stroke_style;
           Stencil stroke = fm->find_by_name ("flags." + font_char);
           if (stroke.is_empty ())
             {
               font_char = dir + stroke_style;
@@ skipping 59 matching lines @@
                " what style of flag glyph is typeset on a"
                " @code{Stem}.  Valid options include @code{'()}"
                " for standard flags, @code{'mensural} and"
                " @code{'no-flag}, which switches off the flag.",
 
                /* properties */
                "glyph-name "
                "style "
                "stroke-style "
               );