X-Git-Url: https://git.donarmstrong.com/?a=blobdiff_plain;f=lily%2Fapply-context-iterator.cc;h=6f69bbc7b8e8843177122d3c51183d5db6897b70;hb=9bea477a992947adbbba48bc479c3f551cde8225;hp=38036708c0dd867c0f966b0c4929032cd1f3093e;hpb=947454c5cc430a9627262de4f25274a64789d3c2;p=lilypond.git

diff --git a/lily/apply-context-iterator.cc b/lily/apply-context-iterator.cc
index 38036708c0..6f69bbc7b8 100644
--- a/lily/apply-context-iterator.cc
+++ b/lily/apply-context-iterator.cc
@@ -1,10 +1,19 @@
+/*
+  apply-context-iterator.cc -- implement Apply_context_iterator
+
+  source file of the GNU LilyPond music typesetter
+
+  (c) 2004--2005 Han-Wen Nienhuys <hanwen@xs4all.nl>
+*/
+
 #include "simple-music-iterator.hh"
 #include "context.hh"
 #include "music.hh"
+#include "input.hh"
 
 /**
-  Iterate a property.  
- */
+   Iterate a property.
+*/
 class Apply_context_iterator : public Simple_music_iterator
 {
 public:
@@ -13,16 +22,18 @@ 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_c_procedure_p (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);
-  
+