[tasque/transition: 81/213] Add default category.

[Antonius Riha <antoniusri src gnome org>]

commit 644f31b4200f6649135629fcb2f7a810ddf11086
Author: Antonius Riha <antoniusriha gmail com>
Date:   Thu Jul 26 17:14:39 2012 +0200

    Add default category.
    
    * This makes life in the ViewModel *much* easier.

 src/libtasque/Backend.cs |   19 +++++++++++++++++++
 1 files changed, 19 insertions(+), 0 deletions(-)
---
diff --git a/src/libtasque/Backend.cs b/src/libtasque/Backend.cs
index e5320b3..8ba6e2e 100644
--- a/src/libtasque/Backend.cs
+++ b/src/libtasque/Backend.cs
@@ -49,6 +49,13 @@ namespace Tasque
 
 			categoriesChangedSources = new List<INotifyCollectionChanged> ();
 			Categories = new SortedNotifyCollection<Category> ();
+			
+			// create default category here, because it is required for the model to be there. Overwrite
+			// default category preferably in child class constructor with more appropriate value
+			var defaultCategory = new Category ("Default");
+			Categories.Add (defaultCategory);
+			DefaultCategory = defaultCategory;
+			
 			Categories.CollectionChanged += HandleCategoriesChanged;
 		}
 
@@ -64,6 +71,17 @@ namespace Tasque
 		/// be shown so the user can configure the backend.
 		/// </value>
 		public abstract bool Configured { get; }
+		
+		public Category DefaultCategory {
+			get { return defaultCategory; }
+			set {
+				if (value == null)
+					throw new ArgumentNullException ("value");
+				if (!Categories.Contains (value))
+					throw new ArgumentException ("Value must be an element of Backend.Categories.", "value");
+				defaultCategory = value;
+			}
+		}
 
 		/// <value>
 		/// Inidication that the backend is initialized
@@ -237,6 +255,7 @@ namespace Tasque
 		}
 
 		List<INotifyCollectionChanged> categoriesChangedSources;
+		Category defaultCategory;
 		SortedNotifyCollection<Task> tasks;
 	}
 }