Added new IMessenger extensions

2026-10-20 14:16:34 +08:00 · 2020-05-16 23:42:46 +02:00
parent 7438772cca
commit b57fea00ee
1 changed files with 107 additions and 0 deletions
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+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System;
+using System.Diagnostics.Contracts;
+
+namespace Microsoft.Toolkit.Mvvm.Messaging
+{
+    /// <summary>
+    /// Extensions for the <see cref="IMessenger"/> type.
+    /// </summary>
+    public static partial class MessengerExtensions
+    {
+        /// <summary>
+        /// Checks whether or not a given recipient has already been registered for a message.
+        /// </summary>
+        /// <typeparam name="TMessage">The type of message to check for the given recipient.</typeparam>
+        /// <param name="messenger">The <see cref="IMessenger"/> instance to use to check the registration.</param>
+        /// <param name="recipient">The target recipient to check the registration for.</param>
+        /// <returns>Whether or not <paramref name="recipient"/> has already been registered for the specified message.</returns>
+        /// <remarks>This method will use the default channel to check for the requested registration.</remarks>
+        [Pure]
+        public static bool IsRegistered<TMessage>(this IMessenger messenger, object recipient)
+            where TMessage : class
+        {
+            return messenger.IsRegistered<TMessage, Unit>(recipient, default);
+        }
+
+        /// <summary>
+        /// Registers a recipient for a given type of message.
+        /// </summary>
+        /// <typeparam name="TMessage">The type of message to receive.</typeparam>
+        /// <param name="messenger">The <see cref="IMessenger"/> instance to use to register the recipient.</param>
+        /// <param name="recipient">The recipient that will receive the messages.</param>
+        /// <param name="action">The <see cref="Action{T}"/> to invoke when a message is received.</param>
+        /// <exception cref="InvalidOperationException">Thrown when trying to register the same message twice.</exception>
+        /// <remarks>This method will use the default channel to perform the requested registration.</remarks>
+        public static void Register<TMessage>(this IMessenger messenger, object recipient, Action<TMessage> action)
+            where TMessage : class
+        {
+            messenger.Register(recipient, default(Unit), action);
+        }
+
+        /// <summary>
+        /// Unregisters a recipient from messages of a given type.
+        /// </summary>
+        /// <typeparam name="TMessage">The type of message to stop receiving.</typeparam>
+        /// <param name="messenger">The <see cref="IMessenger"/> instance to use to unregister the recipient.</param>
+        /// <param name="recipient">The recipient to unregister.</param>
+        /// <remarks>
+        /// This method will unregister the target recipient only from the default channel.
+        /// If the recipient has no registered handler, this method does nothing.
+        /// </remarks>
+        public static void Unregister<TMessage>(this IMessenger messenger, object recipient)
+            where TMessage : class
+        {
+            messenger.Unregister<TMessage, Unit>(recipient, default);
+        }
+
+        /// <summary>
+        /// Sends a message of the specified type to all registered recipients.
+        /// </summary>
+        /// <typeparam name="TMessage">The type of message to send.</typeparam>
+        /// <param name="messenger">The <see cref="IMessenger"/> instance to use to send the message.</param>
+        /// <remarks>
+        /// This method is a shorthand for <see cref="Send{TMessage}(IMessenger,TMessage)"/> when the
+        /// message type exposes a parameterless constructor: it will automatically create
+        /// a new <typeparamref name="TMessage"/> instance and send that to its recipients.
+        /// </remarks>
+        public static void Send<TMessage>(this IMessenger messenger)
+            where TMessage : class, new()
+        {
+            messenger.Send(new TMessage(), default(Unit));
+        }
+
+        /// <summary>
+        /// Sends a message of the specified type to all registered recipients.
+        /// </summary>
+        /// <typeparam name="TMessage">The type of message to send.</typeparam>
+        /// <param name="messenger">The <see cref="IMessenger"/> instance to use to send the message.</param>
+        /// <param name="message">The message to send.</param>
+        public static void Send<TMessage>(this IMessenger messenger, TMessage message)
+            where TMessage : class
+        {
+            messenger.Send(message, default(Unit));
+        }
+
+        /// <summary>
+        /// Sends a message of the specified type to all registered recipients.
+        /// </summary>
+        /// <typeparam name="TMessage">The type of message to send.</typeparam>
+        /// <typeparam name="TToken">The type of token to identify what channel to use to send the message.</typeparam>
+        /// <param name="messenger">The <see cref="IMessenger"/> instance to use to send the message.</param>
+        /// <param name="token">The token indicating what channel to use.</param>
+        /// <remarks>
+        /// This method will automatically create a new <typeparamref name="TMessage"/> instance
+        /// just like <see cref="Send{TMessage}(IMessenger)"/>, and then send it to the right recipients.
+        /// </remarks>
+        public static void Send<TMessage, TToken>(this IMessenger messenger, TToken token)
+            where TMessage : class, new()
+            where TToken : IEquatable<TToken>
+        {
+            messenger.Send(new TMessage(), token);
+        }
+    }
+}