X-Git-Url: https://git.donarmstrong.com/?a=blobdiff_plain;f=lily%2Fapply-context-iterator.cc;h=adf708da35259234ec376c6414ebc904d1110d33;hb=8e6e4cd90a1bd536422ebdec9bc0f2d75a8df7f5;hp=ea01600f6076db680846240f5546c737b7bc014d;hpb=b1323f33e9aa4b9eea05eefb8755c907d4d762d4;p=lilypond.git

diff --git a/lily/apply-context-iterator.cc b/lily/apply-context-iterator.cc
index ea01600f60..adf708da35 100644
--- a/lily/apply-context-iterator.cc
+++ b/lily/apply-context-iterator.cc
@@ -1,28 +1,37 @@
-#include "simple-music-iterator.hh"
+/*
+  apply-context-iterator.cc -- implement Apply_context_iterator
+
+  source file of the GNU LilyPond music typesetter
+
+  (c) 2004--2006 Han-Wen Nienhuys <hanwen@xs4all.nl>
+*/
+
 #include "context.hh"
+#include "input.hh"
+#include "international.hh"
 #include "music.hh"
+#include "simple-music-iterator.hh"
 
-/**
-  Iterate a property.  
- */
 class Apply_context_iterator : public Simple_music_iterator
 {
 public:
-  DECLARE_SCHEME_CALLBACK(constructor, ());
+  DECLARE_SCHEME_CALLBACK (constructor, ());
 protected:
   virtual void process (Moment);
 };
 
-
 void
 Apply_context_iterator::process (Moment m)
 {
   SCM proc = get_music ()->get_property ("procedure");
 
-  scm_call_1 (proc, get_outlet ()->self_scm());
-  
+  if (ly_is_procedure (proc))
+    scm_call_1 (proc, get_outlet ()->self_scm ());
+  else
+    get_music ()->origin ()->warning (_ ("\\applycontext argument is not a procedure"));
+
   Simple_music_iterator::process (m);
 }
 
 IMPLEMENT_CTOR_CALLBACK (Apply_context_iterator);
-  
+