+#ifndef NDEBUG
+static SCM creation_callback = SCM_EOL;
+LY_DEFINE (ly_set_grob_creation_callback, "ly:set-grob-creation-callback",
+ 1, 0, 0, (SCM cb),
+ "Specify a procedure that will be called every time a new grob"
+ " is created. The callback will receive as arguments the grob"
+ " that was created, the name of the C++ source file that caused"
+ " the grob to be created, and the corresponding line number in"
+ " the C++ source file.")
+{
+ LY_ASSERT_TYPE (ly_is_procedure, cb, 1);
+
+ creation_callback = cb;
+
+ return SCM_UNSPECIFIED;
+}
+#endif
+
+Grob *
+Engraver::internal_make_grob (SCM symbol, SCM cause, char const *name, char const *file, int line, char const *fun)
+{
+ (void) file;
+ (void) fun;
+ (void) line;
+ (void) name;
+
+ SCM props = updated_grob_properties (context (), symbol);
+
+ Grob *grob = 0;
+
+ SCM handle = scm_sloppy_assq (ly_symbol2scm ("meta"), props);
+ SCM klass = scm_cdr (scm_sloppy_assq (ly_symbol2scm ("class"), scm_cdr (handle)));
+
+ if (klass == ly_symbol2scm ("Item"))
+ grob = new Item (props);
+ else if (klass == ly_symbol2scm ("Spanner"))
+ grob = new Spanner (props);
+ else if (klass == ly_symbol2scm ("Paper_column"))
+ grob = new Paper_column (props);
+
+ assert (grob);
+ announce_grob (grob, cause);
+
+#ifndef NDEBUG
+ if (ly_is_procedure (creation_callback))
+ scm_apply_0 (creation_callback,
+ scm_list_n (grob->self_scm (), scm_from_locale_string (file),
+ scm_from_int (line), scm_from_locale_string (fun), SCM_UNDEFINED));
+#endif
+
+ return grob;
+}
+
+Item *
+Engraver::internal_make_item (SCM x, SCM cause,
+ char const *name,
+ char const *file, int line, char const *fun)
+{
+ Item *it = dynamic_cast<Item *> (internal_make_grob (x, cause, name, file, line, fun));
+ assert (it);
+ return it;
+}
+
+Paper_column *
+Engraver::internal_make_column (SCM x, char const *name,
+ char const *file, int line, char const *fun)
+{
+ return dynamic_cast<Paper_column *> (internal_make_grob (x, SCM_EOL, name, file, line, fun));
+}
+
+Spanner *
+Engraver::internal_make_spanner (SCM x, SCM cause, char const *name, char const *file, int line, char const *fun)
+{
+ Spanner *sp = dynamic_cast<Spanner *> (internal_make_grob (x, cause, name, file, line, fun));
+ assert (sp);
+ return sp;
+}
+