Implement singleton pattern for thesauruses.

zaaReloaded2/Importer/ZaaImporter/ZaaImporter.cs

@@ -107,8 +107,8 @@ namespace zaaReloaded2.Importer.ZaaImporter
 
         public ZaaImporter()
         {
-            _parameters = new Parameters();
+            _parameters = Parameters.Default;
-            _units = new Units();
+            _units = Units.Default;
         }
 
         #endregion

zaaReloaded2/Thesaurus/Parameters.cs

@@ -32,6 +32,24 @@ namespace zaaReloaded2.Thesaurus
     /// </summary>
     public class Parameters : ThesaurusBase
     {
+        #region Singleton
+
+        private static readonly Parameters _default = new Parameters();
+
+        /// <summary>
+        /// Gets the default singleton instance of the Parameters
+        /// thesaurus.
+        /// </summary>
+        /// <remarks>
+        /// http://csharpindepth.com/Articles/General/Singleton.aspx#cctor
+        /// </remarks>
+        public static Parameters Default { get { return _default; } }
+
+        static Parameters() { }
+        private Parameters() { }
+
+        #endregion
+
         #region Public methods
 
         /// <summary>
@@ -100,5 +118,6 @@ namespace zaaReloaded2.Thesaurus
         }
 
         #endregion
+
     }
 }

zaaReloaded2/Thesaurus/Units.cs

@@ -30,6 +30,23 @@ namespace zaaReloaded2.Thesaurus
     /// </summary>
     public class Units : ThesaurusBase
     {
+        #region Singleton
+
+        private static readonly Units _default = new Units();
+
+        /// <summary>
+        /// Gets the default singleton instance of the Units thesaurus.
+        /// </summary>
+        /// <remarks>
+        /// http://csharpindepth.com/Articles/General/Singleton.aspx#cctor
+        /// </remarks>
+        public static Units Default { get { return _default; } }
+
+        static Units() { }
+        private Units() { }
+
+        #endregion
+
         #region Public methods
 
         /// <summary>