bar-line-engraver and breakpoints

[Joe Neeman]

Is there a reason why breaks are on by default and the barline engraver 
forbids them whenever there is no bar line? It seems simpler for breaks 
to be off by default and to have Paper_column_engraver acknowledge bar 
lines by setting the current column to be breakable. The patch should 
show you what I mean.

If this is an acceptable change then I will use the same structure for 
marking possible page turns.
Index: lily/paper-column-engraver.cc
===================================================================
RCS file: /sources/lilypond/lilypond/lily/paper-column-engraver.cc,v
retrieving revision 1.12
diff -u -r1.12 paper-column-engraver.cc
--- lily/paper-column-engraver.cc       31 Jan 2006 00:30:43 -0000      1.12
+++ lily/paper-column-engraver.cc       26 Feb 2006 21:22:34 -0000
@@ -55,6 +55,8 @@
   p1->set_property ("when", m);
   p2->set_property ("when", m);
 
+  p1->set_property ("breakable", SCM_BOOL_F);
+
   set_columns (p1, p2);
 }
 
@@ -90,6 +92,13 @@
 }
 
 void
+Paper_column_engraver::acknowledge_bar_line (Grob_info gi)
+{
+  if (command_column_)
+    command_column_->set_property ("breakable", SCM_BOOL_T);
+}
+
+void
 Paper_column_engraver::set_columns (Paper_column *new_command,
                                    Paper_column *new_musical)
 {
@@ -108,8 +117,8 @@
 void
 Paper_column_engraver::forbid_breaks ()
 {
-  if (command_column_ && !first_)
-    command_column_->set_property ("breakable", SCM_EOL);
+  /*if (command_column_ && !first_)
+    command_column_->set_property ("breakable", SCM_EOL);*/
 }
 
 bool
@@ -204,6 +213,7 @@
 ADD_ACKNOWLEDGER (Paper_column_engraver, item);
 ADD_ACKNOWLEDGER (Paper_column_engraver, note_spacing);
 ADD_ACKNOWLEDGER (Paper_column_engraver, staff_spacing);
+ADD_ACKNOWLEDGER (Paper_column_engraver, bar_line);
 
 ADD_TRANSLATOR (Paper_column_engraver,
                /* doc */ "Takes care of generating columns."
Index: lily/include/paper-column-engraver.hh
===================================================================
RCS file: /sources/lilypond/lilypond/lily/include/paper-column-engraver.hh,v
retrieving revision 1.8
diff -u -r1.8 paper-column-engraver.hh
--- lily/include/paper-column-engraver.hh       11 Feb 2006 11:35:16 -0000      
1.8
+++ lily/include/paper-column-engraver.hh       26 Feb 2006 21:22:35 -0000
@@ -28,6 +28,7 @@
   DECLARE_ACKNOWLEDGER (item);
   DECLARE_ACKNOWLEDGER (note_spacing);
   DECLARE_ACKNOWLEDGER (staff_spacing);
+  DECLARE_ACKNOWLEDGER (bar_line);
 
   System *system_;
   Music *break_event_;