Doc: Clarify Context creation (3006)

[lilypond.git] / lily / timing-translator.cc

diff --git a/lily/timing-translator.cc b/lily/timing-translator.cc
index 8d456b2d38d537169ee94faa9163e17addd74d33..c6b245ba61b25da7b4a0223bf126d22a069ebdb7 100644 (file)
--- a/lily/timing-translator.cc
+++ b/lily/timing-translator.cc
@@ -46,20 +46,36 @@ Timing_translator::stop_translation_timestep ()
 void
 Timing_translator::initialize ()
 {
-  context ()->add_alias (ly_symbol2scm ("Timing"));
-  context ()->set_property ("currentBarNumber", scm_from_int (1));
-  context ()->set_property ("internalBarNumber", scm_from_int (1));
+  Context *timing = unsmob_context (scm_call_2 (ly_lily_module_constant ("ly:context-find"),
+                                                context ()->self_scm (),
+                                                ly_symbol2scm ("Timing")));
+  if (timing != context ())
+    {
+      context ()->add_alias (ly_symbol2scm ("Timing"));
+
+      if (!timing)
+        {
+          programming_error ("Can't find Timing context template");
+          timing = context ();
+        }
+    }
+
+  SCM barnumber = timing->get_property ("currentBarNumber");
+  if (!scm_is_integer (barnumber))
+    barnumber = scm_from_int (1);
+  context ()->set_property ("currentBarNumber", barnumber);
+  context ()->set_property ("internalBarNumber", barnumber);
 
   context ()->set_property ("timeSignatureFraction",
-                            scm_cons (scm_from_int (4), scm_from_int (4)));
+                            timing->get_property ("timeSignatureFraction"));
   /*
     Do not init measurePosition; this should be done from global
     context.
   */
   context ()->set_property ("measureLength",
-                            Moment (Rational (1)).smobbed_copy ());
+                            timing->get_property ("measureLength"));
   context ()->set_property ("baseMoment",
-                            Moment (Rational (1, 4)).smobbed_copy ());
+                            timing->get_property ("baseMoment"));
 }
 
 Rational
@@ -144,10 +160,12 @@ ADD_TRANSLATOR (Timing_translator,
                 "",
 
                 /* read */
-                "internalBarNumber "
+                "baseMoment "
                 "currentBarNumber "
+                "internalBarNumber "
                 "measureLength "
-                "measurePosition ",
+                "measurePosition "
+                "timeSignatureFraction ",
 
                 /* write */
                 "baseMoment "