Propogate error messages out of deserialization

This is a breaking API change.
jacobdufault · Feb 11, 2014 · aad3948 · aad3948
1 parent b095594
commit aad3948
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Showing 2 changed files with 25 additions and 18 deletions.
diff --git a/Forge.Entities/API/Exceptions.cs b/Forge.Entities/API/Exceptions.cs
@@ -21,6 +21,17 @@
 using System;
 
 namespace Forge.Entities {
+    /// <summary>
+    /// Exception thrown when a deserialization error has occurred. This is most likely during a
+    /// level load.
+    /// </summary>
+    [Serializable]
+    public class DeserializationException : Exception {
+        internal DeserializationException(string json, Exception e) :
+            base("error " + e + " when deserializing " + json) {
+        }
+    }
+
     /// <summary>
     /// Exception thrown when a data type is added to an entity, but the entity already contains an
     /// instance of said data type.

diff --git a/Forge.Entities/API/LevelManagement.cs b/Forge.Entities/API/LevelManagement.cs
@@ -71,13 +71,8 @@ public static string MergeTemplateGroups(IEnumerable<string> groups) {
             // deserialize all of the groups
             List<ITemplateGroup> deserializedGroups = new List<ITemplateGroup>();
             foreach (string serializedGroup in groups) {
-                Maybe<ITemplateGroup> group = LoadTemplateGroup(serializedGroup);
-                if (group.IsEmpty) {
-                    throw new InvalidOperationException("Unable to convert " + serializedGroup +
-                        " to an ITemplateGroup");
-                }
-
-                deserializedGroups.Add(group.Value);
+                var group = LoadTemplateGroup(serializedGroup);
+                deserializedGroups.Add(group);
             }
 
             // merge them
@@ -94,6 +89,7 @@ public static string MergeTemplateGroups(IEnumerable<string> groups) {
         /// <param name="groups">The template groups to merge.</param>
         /// <returns>A single template group that contains all of the templates within the given
         /// groups.</returns>
+        /// <exception cref="InvalidOperationException">There were duplicate TemplateIds</exception>
         public static ITemplateGroup MergeTemplateGroups(IEnumerable<ITemplateGroup> groups) {
             // We store all of our templates in result.
             var result = new TemplateGroup();
@@ -143,37 +139,37 @@ public static string SaveTemplateGroup(ITemplateGroup templates) {
         /// Loads an IGameSnapshot from the given JSON and the given template group. The JSON should
         /// have been generated by calling SaveSnapshot.
         /// </summary>
-        public static Maybe<IGameSnapshot> LoadSnapshot(string snapshotJson, string templateJson) {
+        /// <exception cref="DeserializationException">An error loading the snapshot
+        /// occurred.</exception>
+        public static IGameSnapshot LoadSnapshot(string snapshotJson, string templateJson) {
             try {
                 var restorer = GameSnapshotRestorer.Restore(snapshotJson, templateJson,
                     Maybe<GameEngine>.Empty);
-                return Maybe.Just<IGameSnapshot>(restorer.GameSnapshot);
+                return restorer.GameSnapshot;
             }
             catch (Exception e) {
-                Log.Get(typeof(LevelManager)).Warn(string.Format("Unable to load snapshot from " +
-                    "snapshot={0}, template={1} with error={2}", snapshotJson, templateJson, e));
+                throw new DeserializationException("snapshot=" + snapshotJson +
+                    ", template=" + templateJson, e);
             }
-            return Maybe<IGameSnapshot>.Empty;
         }
 
         /// <summary>
         /// Loads an ITemplateGroup from the given JSON. The JSON should have been generated by
         /// calling SaveTemplates.
         /// </summary>
-        public static Maybe<ITemplateGroup> LoadTemplateGroup(string json) {
+        /// <exception cref="DeserializationException">An error loading the group
+        /// occurred.</exception>
+        public static ITemplateGroup LoadTemplateGroup(string json) {
             try {
                 ITemplateGroup group = SerializationHelpers.Deserialize<TemplateGroup>(json,
                                 RequiredConverters.GetConverters(),
                                 RequiredConverters.GetContextObjects(Maybe<GameEngine>.Empty,
                                     new TemplateConversionContext()));
-                return Maybe.Just(group);
+                return group;
             }
             catch (Exception e) {
-                Log.Get(typeof(LevelManager)).Warn(string.Format("Unable to load template group " +
-                    "from templates={0} with error={1}", json, e));
+                throw new DeserializationException(json, e);
             }
-
-            return Maybe<ITemplateGroup>.Empty;
         }
     }
 }