use Audio_note::get_column() rather than directly accessing the member field

This adheres to the principle of encapsulation.

diff --git a/lily/midi-walker.cc b/lily/midi-walker.cc
index 6d0b1290a38491f3f8c47f21d7063ab88f47b3a1..b97630b0d147ed8ebc05d63c111b8928c3667cad 100644 (file)
--- a/lily/midi-walker.cc
+++ b/lily/midi-walker.cc
@@ -178,7 +178,8 @@ void
 Midi_walker::process ()
 {
   Audio_item *audio = items_[index_];
-  do_stop_notes (audio->audio_column_->ticks ());
+  Audio_column *col = audio->get_column ();
+  do_stop_notes (col->ticks ());
 
   if (Midi_item *midi = get_midi (audio))
     {