Rework event contexts in C#

examples~/quickstart/client/Program.cs

@@ -104,27 +104,21 @@ void Message_OnInsert(EventContext ctx, Message insertedValue)
     }
 }
 
-void Reducer_OnSetNameEvent(EventContext ctx, string name)
+void Reducer_OnSetNameEvent(ReducerEventContext ctx, string name)
 {
-    if (ctx.Event is Event<Reducer>.Reducer reducer)
+    var e = ctx.Event;
+    if (e.CallerIdentity == local_identity && e.Status is Status.Failed(var error))
     {
-        var e = reducer.ReducerEvent;
-        if (e.CallerIdentity == local_identity && e.Status is Status.Failed(var error))
-        {
-            Console.Write($"Failed to change name to {name}: {error}");
-        }
+        Console.Write($"Failed to change name to {name}: {error}");
     }
 }
 
-void Reducer_OnSendMessageEvent(EventContext ctx, string text)
+void Reducer_OnSendMessageEvent(ReducerEventContext ctx, string text)
 {
-    if (ctx.Event is Event<Reducer>.Reducer reducer)
+    var e = ctx.Event;
+    if (e.CallerIdentity == local_identity && e.Status is Status.Failed(var error))
     {
-        var e = reducer.ReducerEvent;
-        if (e.CallerIdentity == local_identity && e.Status is Status.Failed(var error))
-        {
-            Console.Write($"Failed to send message {text}: {error}");
-        }
+        Console.Write($"Failed to send message {text}: {error}");
     }
 }
 
@@ -134,7 +128,7 @@ void OnConnect(DbConnection conn, Identity identity, string authToken)
     AuthToken.SaveToken(authToken);
 
     var subscriptions = 0;
-    SubscriptionBuilder<EventContext>.Callback waitForSubscriptions = (EventContext ctx) =>
+    Action<SubscriptionEventContext> waitForSubscriptions = (SubscriptionEventContext ctx) =>
     {
         // Note: callbacks are always invoked on the main thread, so you don't need to
         // worry about thread synchronization or anything like that.
@@ -176,7 +170,7 @@ void PrintMessagesInOrder(RemoteTables tables)
     }
 }
 
-void OnSubscriptionApplied(EventContext ctx)
+void OnSubscriptionApplied(SubscriptionEventContext ctx)
 {
     Console.WriteLine("Connected");
     PrintMessagesInOrder(ctx.Db);

examples~/quickstart/client/module_bindings/Reducers/IdentityConnected.g.cs

@@ -12,10 +12,10 @@ namespace SpacetimeDB.Types
 {
     public sealed partial class RemoteReducers : RemoteBase
     {
-        public delegate void IdentityConnectedHandler(EventContext ctx);
+        public delegate void IdentityConnectedHandler(ReducerEventContext ctx);
         public event IdentityConnectedHandler? OnIdentityConnected;
 
-        public bool InvokeIdentityConnected(EventContext ctx, Reducer.IdentityConnected args)
+        public bool InvokeIdentityConnected(ReducerEventContext ctx, Reducer.IdentityConnected args)
         {
             if (OnIdentityConnected == null) return false;
             OnIdentityConnected(

examples~/quickstart/client/module_bindings/Reducers/IdentityDisconnected.g.cs

@@ -12,10 +12,10 @@ namespace SpacetimeDB.Types
 {
     public sealed partial class RemoteReducers : RemoteBase
     {
-        public delegate void IdentityDisconnectedHandler(EventContext ctx);
+        public delegate void IdentityDisconnectedHandler(ReducerEventContext ctx);
         public event IdentityDisconnectedHandler? OnIdentityDisconnected;
 
-        public bool InvokeIdentityDisconnected(EventContext ctx, Reducer.IdentityDisconnected args)
+        public bool InvokeIdentityDisconnected(ReducerEventContext ctx, Reducer.IdentityDisconnected args)
         {
             if (OnIdentityDisconnected == null) return false;
             OnIdentityDisconnected(

examples~/quickstart/client/module_bindings/Reducers/SendMessage.g.cs

@@ -12,15 +12,15 @@ namespace SpacetimeDB.Types
 {
     public sealed partial class RemoteReducers : RemoteBase
     {
-        public delegate void SendMessageHandler(EventContext ctx, string text);
+        public delegate void SendMessageHandler(ReducerEventContext ctx, string text);
         public event SendMessageHandler? OnSendMessage;
 
         public void SendMessage(string text)
         {
             conn.InternalCallReducer(new Reducer.SendMessage(text), this.SetCallReducerFlags.SendMessageFlags);
         }
 
-        public bool InvokeSendMessage(EventContext ctx, Reducer.SendMessage args)
+        public bool InvokeSendMessage(ReducerEventContext ctx, Reducer.SendMessage args)
         {
             if (OnSendMessage == null) return false;
             OnSendMessage(

examples~/quickstart/client/module_bindings/Reducers/SetName.g.cs

@@ -12,15 +12,15 @@ namespace SpacetimeDB.Types
 {
     public sealed partial class RemoteReducers : RemoteBase
     {
-        public delegate void SetNameHandler(EventContext ctx, string name);
+        public delegate void SetNameHandler(ReducerEventContext ctx, string name);
         public event SetNameHandler? OnSetName;
 
         public void SetName(string name)
         {
             conn.InternalCallReducer(new Reducer.SetName(name), this.SetCallReducerFlags.SetNameFlags);
         }
 
-        public bool InvokeSetName(EventContext ctx, Reducer.SetName args)
+        public bool InvokeSetName(ReducerEventContext ctx, Reducer.SetName args)
         {
             if (OnSetName == null) return false;
             OnSetName(

examples~/quickstart/client/module_bindings/SpacetimeDBClient.g.cs

@@ -26,6 +26,7 @@ public RemoteTables(DbConnection conn)
     }
 
     public sealed partial class SetReducerFlags { }
+
     public sealed class EventContext : IEventContext
     {
         private readonly DbConnection conn;
@@ -35,13 +36,67 @@ public sealed class EventContext : IEventContext
         public RemoteReducers Reducers => conn.Reducers;
         public SetReducerFlags SetReducerFlags => conn.SetReducerFlags;
 
-        internal EventContext(DbConnection conn, Event<Reducer> reducerEvent)
+        internal EventContext(DbConnection conn, Event<Reducer> Event)
+        {
+            this.conn = conn;
+            this.Event = Event;
+        }
+    }
+
+    public sealed class ReducerEventContext : IReducerEventContext
+    {
+        private readonly DbConnection conn;
+        public readonly ReducerEvent<Reducer> Event;
+
+        public RemoteTables Db => conn.Db;
+        public RemoteReducers Reducers => conn.Reducers;
+        public SetReducerFlags SetReducerFlags => conn.SetReducerFlags;
+
+        internal ReducerEventContext(DbConnection conn, ReducerEvent<Reducer> reducerEvent)
         {
             this.conn = conn;
             Event = reducerEvent;
         }
     }
 
+    public sealed class ErrorContext : IErrorContext
+    {
+        private readonly DbConnection conn;
+        public readonly Exception Event;
+        Exception IErrorContext.Event
+        {
+            get
+            {
+                return Event;
+            }
+        }
+
+        public RemoteTables Db => conn.Db;
+        public RemoteReducers Reducers => conn.Reducers;
+        public SetReducerFlags SetReducerFlags => conn.SetReducerFlags;
+        public Exception Error => Event;
+
+        internal ErrorContext(DbConnection conn, Exception error)
+        {
+            this.conn = conn;
+            Event = error;
+        }
+    }
+
+    public sealed class SubscriptionEventContext : ISubscriptionEventContext
+    {
+        private readonly DbConnection conn;
+
+        public RemoteTables Db => conn.Db;
+        public RemoteReducers Reducers => conn.Reducers;
+        public SetReducerFlags SetReducerFlags => conn.SetReducerFlags;
+
+        internal SubscriptionEventContext(DbConnection conn)
+        {
+            this.conn = conn;
+        }
+    }
+
     public abstract partial class Reducer
     {
         private Reducer() { }
@@ -75,12 +130,21 @@ protected override Reducer ToReducer(TransactionUpdate update)
             };
         }
 
-        protected override IEventContext ToEventContext(Event<Reducer> reducerEvent) =>
-        new EventContext(this, reducerEvent);
+        protected override IEventContext ToEventContext(Event<Reducer> Event) =>
+        new EventContext(this, Event);
+
+        protected override IReducerEventContext ToReducerEventContext(ReducerEvent<Reducer> reducerEvent) =>
+        new ReducerEventContext(this, reducerEvent);
+
+        protected override ISubscriptionEventContext MakeSubscriptionEventContext() =>
+        new SubscriptionEventContext(this);
+
+        protected override IErrorContext ToErrorContext(Exception exception) =>
+        new ErrorContext(this, exception);
 
-        protected override bool Dispatch(IEventContext context, Reducer reducer)
+        protected override bool Dispatch(IReducerEventContext context, Reducer reducer)
         {
-            var eventContext = (EventContext)context;
+            var eventContext = (ReducerEventContext)context;
             return reducer switch
             {
                 Reducer.IdentityConnected args => Reducers.InvokeIdentityConnected(eventContext, args),
@@ -92,6 +156,6 @@ protected override bool Dispatch(IEventContext context, Reducer reducer)
             };
         }
 
-        public SubscriptionBuilder<EventContext> SubscriptionBuilder() => new(this);
+        public SubscriptionBuilder<SubscriptionEventContext, ErrorContext> SubscriptionBuilder() => new(this);
     }
 }