X-Git-Url: https://git.donarmstrong.com/?a=blobdiff_plain;f=lily%2Flistener.cc;h=c785ff3d72d502302f4f6ba98fbaaa91fbf6d018;hb=deafba084c8ecf6af02f64455856147821b598c7;hp=edc96bdf1c84aed5a51c69b87ae4914a125ebe77;hpb=c83f8abe0c27faabcad658ff3a9691158c62c3a3;p=lilypond.git

diff --git a/lily/listener.cc b/lily/listener.cc
index edc96bdf1c..c785ff3d72 100644
--- a/lily/listener.cc
+++ b/lily/listener.cc
@@ -1,15 +1,32 @@
 /*
-  listener.cc -- implement Listener and Listener_target
+  This file is part of LilyPond, the GNU music typesetter.
 
-  source file of the GNU LilyPond music typesetter
+  Copyright (C) 2005 Erik Sandberg  <mandolaerik@gmail.com>
 
-  (c) 2005 Erik Sandberg  <mandolaerik@gmail.com>
+  LilyPond is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  LilyPond is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with LilyPond.  If not, see <http://www.gnu.org/licenses/>.
 */
 
 #include "listener.hh"
 #include "ly-smobs.icc"
 #include "warn.hh"
 
+Listener::Listener ()
+{
+  target_ = 0;
+  type_ = 0;
+}
+
 Listener::Listener (const void *target, Listener_function_table *type)
 {
   target_ = (void *)target;
@@ -19,10 +36,11 @@ Listener::Listener (const void *target, Listener_function_table *type)
 Listener::Listener (Listener const &other)
 {
   target_ = other.target_;
-  type_ = other.type_; 
+  type_ = other.type_;
 }
 
-void Listener::listen (SCM ev) const {
+void Listener::listen (SCM ev) const
+{
   (type_->listen_callback) (target_, ev);
 }
 
@@ -30,12 +48,13 @@ SCM
 Listener::mark_smob (SCM sm)
 {
   Listener *me = (Listener *) SCM_CELL_WORD_1 (sm);
-  (me->type_->mark_callback) (me->target_);
+  if (me->type_)
+    (me->type_->mark_callback) (me->target_);
   return SCM_EOL;
 }
 
 int
-Listener::print_smob (SCM s, SCM p, scm_print_state*)
+Listener::print_smob (SCM, SCM p, scm_print_state *)
 {
   scm_puts ("#<Listener>", p);
   return 1;
@@ -51,4 +70,4 @@ Listener::equal_p (SCM a, SCM b)
 }
 
 IMPLEMENT_SIMPLE_SMOBS (Listener);
-IMPLEMENT_TYPE_P (Listener, "listener");
+IMPLEMENT_TYPE_P (Listener, "ly:listener?");