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Riptide/MessageHandlerAttribute.cs

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+// This file is provided under The MIT License as part of RiptideNetworking.
+// Copyright (c) Tom Weiland
+// For additional information please see the included LICENSE.md file or view it on GitHub:
+// https://github.com/RiptideNetworking/Riptide/blob/main/LICENSE.md
+
+using System;
+
+namespace Riptide
+{
+    /// <summary>Specifies a method as the message handler for messages with the given ID.</summary>
+    /// <remarks>
+    ///   <para>
+    ///     In order for a method to qualify as a message handler, it <i>must</i> match a valid message handler method signature. <see cref="Server"/>s
+    ///     will only use methods marked with this attribute if they match the <see cref="Server.MessageHandler"/> signature, and <see cref="Client"/>s
+    ///     will only use methods marked with this attribute if they match the <see cref="Client.MessageHandler"/> signature.
+    ///   </para>
+    ///   <para>
+    ///     Methods marked with this attribute which match neither of the valid message handler signatures will not be used by <see cref="Server"/>s
+    ///     or <see cref="Client"/>s and will cause warnings at runtime.
+    ///   </para>
+    ///   <para>
+    ///     If you want a <see cref="Server"/> or <see cref="Client"/> to only use a subset of all message handler methods, you can do so by setting up
+    ///     custom message handler groups. Simply set the group ID in the <see cref="MessageHandlerAttribute(ushort, byte)"/> constructor and pass the
+    ///     same value to the <see cref="Server.Start(ushort, ushort, byte, bool)"/> or <see cref="Client.Connect(string, int, byte, Message, bool)"/> method. This
+    ///     will make that <see cref="Server"/> or <see cref="Client"/> only use message handlers which have the same group ID.
+    ///   </para>
+    /// </remarks>
+    [AttributeUsage(AttributeTargets.Method, Inherited = false, AllowMultiple = false)]
+    public sealed class MessageHandlerAttribute : Attribute
+    {
+        /// <summary>The ID of the message type which this method is meant to handle.</summary>
+        public readonly ushort MessageId;
+        /// <summary>The ID of the group of message handlers which this method belongs to.</summary>
+        public readonly byte GroupId;
+
+        /// <summary>Initializes a new instance of the <see cref="MessageHandlerAttribute"/> class with the <paramref name="messageId"/> and <paramref name="groupId"/> values.</summary>
+        /// <param name="messageId">The ID of the message type which this method is meant to handle.</param>
+        /// <param name="groupId">The ID of the group of message handlers which this method belongs to.</param>
+        /// <remarks>
+        ///   <see cref="Server"/>s will only use this method if its signature matches the <see cref="Server.MessageHandler"/> signature.
+        ///   <see cref="Client"/>s will only use this method if its signature matches the <see cref="Client.MessageHandler"/> signature.
+        ///   This method will be ignored if its signature matches neither of the valid message handler signatures.
+        /// </remarks>
+        public MessageHandlerAttribute(ushort messageId, byte groupId = 0)
+        {
+            MessageId = messageId;
+            GroupId = groupId;
+        }
+    }
+}