r3089 - /1.3/data/main.py -- March 07, 2007 - 09:36

Author: bugman
Date: Wed Mar  7 09:36:19 2007
New Revision: 3089

URL: http://svn.gna.org/viewcvs/relax?rev=3089&view=rev
Log:
Converted the Data() class from the 'data' directory into a singleton.

For more infomation about this usage of the singleton design pattern, see my 
post at
https://mail.gna.org/public/relax-devel/2007-03/msg00012.html (Message-id:
<7f080ed10703070006s309a1e1do38e621f48d8f6d9e@xxxxxxxxxxxxxx>).


Modified:
    1.3/data/main.py

Modified: 1.3/data/main.py
URL: 
http://svn.gna.org/viewcvs/relax/1.3/data/main.py?rev=3089&r1=3088&r2=3089&view=diff
==============================================================================
--- 1.3/data/main.py (original)
+++ 1.3/data/main.py Wed Mar  7 09:36:19 2007
@@ -1,6 +1,6 @@
 
###############################################################################
 #                                                                            
 #
-# Copyright (C) 2003, 2004, 2006 Edward d'Auvergne                           
 #
+# Copyright (C) 2003-2004, 2006-2007 Edward d'Auvergne                       
 #
 #                                                                            
 #
 # This file is part of the program relax.                                    
 #
 #                                                                            
 #
@@ -33,7 +33,9 @@
 # Global data.
 ##############
 
-class Data:
+class Data(object):
+    __instance = None
+
     def __init__(self):
         """Class containing all the program data."""
 
@@ -70,6 +72,22 @@
         self.warning = {}
 
 
+    def __new__(self, *args, **kargs): 
+        """Method for implementing the singleton design pattern.
+
+        If no other class instance currently exists, create a new instance 
of this class.  Otherwise
+        return the class instance.  See 
http://en.wikipedia.org/wiki/Singleton_pattern for a
+        description of this design pattern.
+        """
+
+        # Create a new instance if none exists.
+        if self.__instance is None:
+            self.__instance = object.__new__(self, *args, **kargs)
+
+        # Return the class instance.
+        return self.__instance
+
+
     def __repr__(self):
         text = "The data class containing all permanent program data.\n"
         text = text + "The class contains the following objects:\n"