[vala] Report error when trying to use signals as expressions

[Jürg Billeter <juergbi src gnome org>]

commit 49c419a1b0e4157fefdc35e8160dda16f388ac88
Author: Jürg Billeter <j bitron ch>
Date:   Mon Apr 6 18:21:47 2009 +0200

    Report error when trying to use signals as expressions
    
    Fixes bug 437431.
---
 vala/valasignaltype.vala |   10 +++++++++-
 1 files changed, 9 insertions(+), 1 deletions(-)

diff --git a/vala/valasignaltype.vala b/vala/valasignaltype.vala
index 3157a64..e934403 100644
--- a/vala/valasignaltype.vala
+++ b/vala/valasignaltype.vala
@@ -1,6 +1,6 @@
 /* valasignaltype.vala
  *
- * Copyright (C) 2007-2008  Jürg Billeter
+ * Copyright (C) 2007-2009  Jürg Billeter
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
@@ -48,4 +48,12 @@ public class Vala.SignalType : DataType {
 	public override DataType copy () {
 		return new SignalType (signal_symbol);
 	}
+
+	public override bool compatible (DataType target_type) {
+		return false;
+	}
+
+	public override string to_qualified_string (Scope? scope) {
+		return signal_symbol.get_full_name ();
+	}
 }