[banshee] [Configuration] Refactor ConfigurationClients

[Gabriel Burt <gburt src gnome org>]

commit f5ba0a09c77bda80d1913280814fab0916113c84
Author: Gabriel Burt <gabriel burt gmail com>
Date:   Thu Nov 18 11:06:56 2010 -0600

    [Configuration] Refactor ConfigurationClients
    
    And add bool TryGet<T> function that returns false if no such key/value
    pair exists.

 .../GConfConfigurationClient.cs                    |   36 +++-------------
 .../Banshee.Configuration/ConfigurationClient.cs   |   26 +++++++-----
 .../Banshee.Configuration/IConfigurationClient.cs  |   42 ++++++++++++++++---
 .../MemoryConfigurationClient.cs                   |   40 +++---------------
 .../XmlConfigurationClient.cs                      |   38 ++++++------------
 .../DatabaseConfigurationClient.cs                 |   39 +++---------------
 .../Banshee.Database/SortKeyUpdater.cs             |    1 +
 7 files changed, 85 insertions(+), 137 deletions(-)
---
diff --git a/src/Backends/Banshee.Gnome/Banshee.GnomeBackend/GConfConfigurationClient.cs b/src/Backends/Banshee.Gnome/Banshee.GnomeBackend/GConfConfigurationClient.cs
index 69635b3..9372b6f 100644
--- a/src/Backends/Banshee.Gnome/Banshee.GnomeBackend/GConfConfigurationClient.cs
+++ b/src/Backends/Banshee.Gnome/Banshee.GnomeBackend/GConfConfigurationClient.cs
@@ -102,25 +102,11 @@ namespace Banshee.GnomeBackend
             }
         }
 
-        public T Get<T> (SchemaEntry<T> entry)
-        {
-            return Get<T> (entry.Namespace, entry.Key, entry.DefaultValue);
-        }
-
-        public T Get<T> (SchemaEntry<T> entry, T fallback)
-        {
-            return Get<T> (entry.Namespace, entry.Key, fallback);
-        }
-
-        public T Get<T> (string key, T fallback)
-        {
-            return Get<T> (null, key, fallback);
-        }
-
-        public T Get<T> (string @namespace, string key, T fallback)
+        public bool TryGet<T> (string @namespace, string key, out T result)
         {
             if (DisableGConf || key == null) {
-                return fallback;
+                result = default (T);
+                return false;
             }
 
             if (client == null) {
@@ -128,23 +114,15 @@ namespace Banshee.GnomeBackend
             }
 
             try {
-                return (T)client.Get (CreateKey (@namespace, key));
+                result = (T)client.Get (CreateKey (@namespace, key));
+                return true;
             } catch (GConf.NoSuchKeyException) {
-                return fallback;
             } catch (Exception e) {
                 Log.Exception (String.Format ("Could no read GConf key {0}.{1}", @namespace, key), e);
-                return fallback;
             }
-        }
 
-        public void Set<T> (SchemaEntry<T> entry, T value)
-        {
-            Set<T> (entry.Namespace, entry.Key, value);
-        }
-
-        public void Set<T> (string key, T value)
-        {
-            Set<T> (null, key, value);
+            result = default (T);
+            return false;
         }
 
         public void Set<T> (string @namespace, string key, T value)
diff --git a/src/Core/Banshee.Core/Banshee.Configuration/ConfigurationClient.cs b/src/Core/Banshee.Core/Banshee.Configuration/ConfigurationClient.cs
index e8134dc..7534c04 100644
--- a/src/Core/Banshee.Core/Banshee.Configuration/ConfigurationClient.cs
+++ b/src/Core/Banshee.Core/Banshee.Configuration/ConfigurationClient.cs
@@ -78,34 +78,40 @@ namespace Banshee.Configuration
             }
         }
 
-        public static T Get<T> (SchemaEntry<T> entry)
+        public static T Get<T>(SchemaEntry<T> entry)
         {
-            return Client.Get<T> (entry);
+            return Get<T>(entry.Namespace, entry.Key, entry.DefaultValue);
         }
 
-        public static T Get<T> (SchemaEntry<T> entry, T fallback)
+        public static T Get<T>(SchemaEntry<T> entry, T fallback)
         {
-            return Client.Get<T> (entry, fallback);
+            return Get<T>(entry.Namespace, entry.Key, fallback);
         }
 
-        public static T Get<T> (string key, T fallback)
+        public static T Get<T>(string key, T fallback)
         {
-            return Client.Get<T> (key, fallback);
+            return Get<T>(null, key, fallback);
         }
 
-        public static T Get<T> (string @namespace, string key, T fallback)
+        public static T Get<T>(string namespce, string key, T fallback)
         {
-            return Client.Get<T> (@namespace, key, fallback);
+            T result;
+            return TryGet<T> (namespce, key, out result) ? result : fallback;
+        }
+
+        public static bool TryGet<T> (string @namespace, string key, out T result)
+        {
+            return Client.TryGet<T> (@namespace, key, out result);
         }
 
         public static void Set<T> (SchemaEntry<T> entry, T value)
         {
-            Client.Set<T> (entry, value);
+            Set (entry.Namespace, entry.Key, value);
         }
 
         public static void Set<T> (string key, T value)
         {
-            Client.Set<T> (key, value);
+            Set (null, key, value);
         }
 
         public static void Set<T> (string @namespace, string key, T value)
diff --git a/src/Core/Banshee.Core/Banshee.Configuration/IConfigurationClient.cs b/src/Core/Banshee.Core/Banshee.Configuration/IConfigurationClient.cs
index 10064ba..d7831c3 100644
--- a/src/Core/Banshee.Core/Banshee.Configuration/IConfigurationClient.cs
+++ b/src/Core/Banshee.Core/Banshee.Configuration/IConfigurationClient.cs
@@ -30,13 +30,41 @@ namespace Banshee.Configuration
 {
     public interface IConfigurationClient
     {
-        T Get<T> (SchemaEntry<T> entry);
-        T Get<T> (SchemaEntry<T> entry, T fallback);
-        T Get<T> (string key, T fallback);
-        T Get<T> (string @namespace, string key, T fallback);
-
-        void Set<T> (SchemaEntry<T> entry, T value);
-        void Set<T> (string key, T value);
+        bool TryGet<T> (string @namespace, string key, out T result);
         void Set<T> (string @namespace, string key, T value);
     }
+
+    public static class Extensions
+    {
+        public static T Get<T> (this IConfigurationClient client, SchemaEntry<T> entry)
+        {
+            return client.Get<T> (entry.Namespace, entry.Key, entry.DefaultValue);
+        }
+
+        public static T Get<T> (this IConfigurationClient client, SchemaEntry<T> entry, T fallback)
+        {
+            return client.Get<T> (entry.Namespace, entry.Key, fallback);
+        }
+
+        public static T Get<T> (this IConfigurationClient client, string key, T fallback)
+        {
+            return client.Get<T> (null, key, fallback);
+        }
+
+        public static T Get<T> (this IConfigurationClient client, string namespce, string key, T fallback)
+        {
+            T result;
+            return client.TryGet<T> (namespce, key, out result) ? result : fallback;
+        }
+
+        public static void Set<T> (this IConfigurationClient client, SchemaEntry<T> entry, T value)
+        {
+            client.Set (entry.Namespace, entry.Key, value);
+        }
+
+        public static void Set<T> (this IConfigurationClient client, string key, T value)
+        {
+            client.Set (null, key, value);
+        }
+    }
 }
diff --git a/src/Core/Banshee.Core/Banshee.Configuration/MemoryConfigurationClient.cs b/src/Core/Banshee.Core/Banshee.Configuration/MemoryConfigurationClient.cs
index 8f62aad..a4a7fc9 100644
--- a/src/Core/Banshee.Core/Banshee.Configuration/MemoryConfigurationClient.cs
+++ b/src/Core/Banshee.Core/Banshee.Configuration/MemoryConfigurationClient.cs
@@ -35,38 +35,9 @@ namespace Banshee.Configuration
     {
         private Dictionary<string, object> config = new Dictionary<string, object> ();
 
-#region Helper Overrides
-
-        public T Get<T> (SchemaEntry<T> entry)
-        {
-            return Get (entry.Namespace, entry.Key, entry.DefaultValue);
-        }
-
-        public T Get<T> (SchemaEntry<T> entry, T fallback)
-        {
-            return Get (entry.Namespace, entry.Key, fallback);
-        }
-
-        public T Get<T> (string key, T fallback)
-        {
-            return Get (null, key, fallback);
-        }
-
-        public void Set<T> (SchemaEntry<T> entry, T value)
-        {
-            Set (entry.Namespace, entry.Key, value);
-        }
-
-        public void Set<T> (string key, T value)
-        {
-            Set (null, key, value);
-        }
-
-#endregion
-
 #region Implementation
 
-        public T Get<T> (string namespce, string key, T fallback)
+        public bool TryGet<T> (string namespce, string key, out T result)
         {
             lock (this) {
                 string fq_key = MakeKey (namespce, key);
@@ -74,13 +45,16 @@ namespace Banshee.Configuration
 
                 if (config.TryGetValue (fq_key, out value)) {
                     if (value == null) {
-                        return default (T);
+                        result = default (T);
+                        return true;
                     } else if (value.GetType () == typeof (T)) {
-                        return (T)value;
+                        result = (T)value;
+                        return true;
                     }
                 }
 
-                return fallback;
+                result = default (T);
+                return false;
             }
         }
 
diff --git a/src/Core/Banshee.Core/Banshee.Configuration/XmlConfigurationClient.cs b/src/Core/Banshee.Core/Banshee.Configuration/XmlConfigurationClient.cs
index 4eb6b04..a19a451 100644
--- a/src/Core/Banshee.Core/Banshee.Configuration/XmlConfigurationClient.cs
+++ b/src/Core/Banshee.Core/Banshee.Configuration/XmlConfigurationClient.cs
@@ -86,41 +86,27 @@ namespace Banshee.Configuration
             }
         }
 
-        public T Get<T>(SchemaEntry<T> entry)
-        {
-            return Get<T>(entry.Namespace, entry.Key, entry.DefaultValue);
-        }
-
-        public T Get<T>(SchemaEntry<T> entry, T fallback)
-        {
-            return Get<T>(entry.Namespace, entry.Key, fallback);
-        }
-
-        public T Get<T>(string key, T fallback)
-        {
-            return Get<T>(null, key, fallback);
-        }
-
-        public T Get<T>(string namespce, string key, T fallback)
+        public bool TryGet<T>(string namespce, string key, out T result)
         {
             lock(xml_document) {
                 XmlNode namespace_node = GetNamespaceNode(namespce == null
                     ? new string [] {null_namespace}
                     : namespce.Split('.'), false);
 
-                if(namespace_node == null) {
-                    return fallback;
-                }
-
-                foreach(XmlNode node in namespace_node.ChildNodes) {
-                    if(node.Attributes[tag_identifier_attribute_name].Value == key && node.Name == value_tag_name) {
-                        XmlSerializer serializer = new XmlSerializer(typeof(T));
-                        using (var reader = new StringReader(node.InnerXml) ) {
-                            return (T) serializer.Deserialize(reader);
+                if(namespace_node != null) {
+                    foreach(XmlNode node in namespace_node.ChildNodes) {
+                        if(node.Attributes[tag_identifier_attribute_name].Value == key && node.Name == value_tag_name) {
+                            XmlSerializer serializer = new XmlSerializer(typeof(T));
+                            using (var reader = new StringReader(node.InnerXml) ) {
+                                result = (T) serializer.Deserialize(reader);
+                                return true;
+                            }
                         }
                     }
                 }
-                return fallback;
+
+                result = default (T);
+                return false;
             }
         }
 
diff --git a/src/Core/Banshee.Services/Banshee.Configuration/DatabaseConfigurationClient.cs b/src/Core/Banshee.Services/Banshee.Configuration/DatabaseConfigurationClient.cs
index 7a60603..3097c4e 100644
--- a/src/Core/Banshee.Services/Banshee.Configuration/DatabaseConfigurationClient.cs
+++ b/src/Core/Banshee.Services/Banshee.Configuration/DatabaseConfigurationClient.cs
@@ -63,34 +63,19 @@ namespace Banshee.Configuration
                 "UPDATE {0} SET Value=? WHERE Key=?", TableName));
         }
 
-        public T Get <T> (SchemaEntry<T> entry)
-        {
-            return Get (entry.Namespace, entry.Key, entry.DefaultValue);
-        }
-
-        public T Get <T> (SchemaEntry<T> entry, T fallback)
-        {
-            return Get (entry.Namespace, entry.Key, fallback);
-        }
-
-        public T Get <T> (string key, T fallback)
-        {
-            return Get (null, key, fallback);
-        }
-
-        public T Get <T> (string namespce, string key, T fallback)
+        public bool TryGet <T> (string namespce, string key, out T result)
         {
             try {
                 using (IDataReader reader = Get (namespce, key)) {
                     if (reader.Read ()) {
-                        return (T) Convert.ChangeType (reader[0], typeof (T));
-                    } else {
-                        return fallback;
+                        result = (T) Convert.ChangeType (reader[0], typeof (T));
+                        return true;
                     }
                 }
-            } catch {
-                return fallback;
-            }
+            } catch {}
+
+            result = default (T);
+            return false;
         }
 
         private IDataReader Get (string namespce, string key)
@@ -99,16 +84,6 @@ namespace Banshee.Configuration
                 Banshee.Configuration.MemoryConfigurationClient.MakeKey (namespce, key));
         }
 
-        public void Set <T> (SchemaEntry<T> entry, T value)
-        {
-            Set (entry.Namespace, entry.Key, value);
-        }
-
-        public void Set <T> (string key, T value)
-        {
-            Set (null, key, value);
-        }
-
         public void Set <T> (string namespce, string key, T value)
         {
             string fq_key = Banshee.Configuration.MemoryConfigurationClient.MakeKey (namespce, key);
diff --git a/src/Core/Banshee.Services/Banshee.Database/SortKeyUpdater.cs b/src/Core/Banshee.Services/Banshee.Database/SortKeyUpdater.cs
index 8a6d7e2..5d93cec 100644
--- a/src/Core/Banshee.Services/Banshee.Database/SortKeyUpdater.cs
+++ b/src/Core/Banshee.Services/Banshee.Database/SortKeyUpdater.cs
@@ -25,6 +25,7 @@
 //
 
 using System;
+using System.Linq;
 using System.Globalization;
 
 using Banshee.Collection;