From d291a99ee339d3b4b0fb33c825f2a76b6ce867be Mon Sep 17 00:00:00 2001
From: CvekCoding <36374606+CvekCoding@users.noreply.github.com>
Date: Mon, 24 Feb 2020 21:16:59 +0300
Subject: [PATCH] Bus restricting with Interfaces

Proposed more flexible way to restrict handlers with buses - use interfaces for this.
---
 messenger/multiple_buses.rst | 79 +++++++++++++++++++++---------------
 service_container/tags.rst   |  2 +
 2 files changed, 48 insertions(+), 33 deletions(-)

diff --git a/messenger/multiple_buses.rst b/messenger/multiple_buses.rst
index 5136553dac2..c79aeb7b2b7 100644
--- a/messenger/multiple_buses.rst
+++ b/messenger/multiple_buses.rst
@@ -150,30 +150,30 @@ you can restrict each handler to a specific bus using the ``messenger.message_ha
 This way, the ``App\MessageHandler\SomeCommandHandler`` handler will only be
 known by the ``command.bus`` bus.
 
-You can also automatically add this tag to a number of classes by following
-a naming convention and registering all of the handler services by name with
-the correct tag:
+You can also automatically add this tag to a number of classes by using
+the :ref:`_instanceof service configuration <di-instanceof>`. Using this,
+you can determine the message bus based on an implemented interface:
 
 .. configuration-block::
 
     .. code-block:: yaml
 
         # config/services.yaml
+        services:
+            # ...
+
+            _instanceof:
+                # all services implementing the CommandHandlerInterface
+                # will be registered on the command.bus bus
+                App\MessageHandler\CommandHandlerInterface:
+                    tags:
+                        - { name: messenger.message_handler, bus: command.bus }
 
-        # put this after the "App\" line that registers all your services
-        command_handlers:
-            namespace: App\MessageHandler\
-            resource: '%kernel.project_dir%/src/MessageHandler/*CommandHandler.php'
-            autoconfigure: false
-            tags:
-                - { name: messenger.message_handler, bus: command.bus }
-
-        query_handlers:
-            namespace: App\MessageHandler\
-            resource: '%kernel.project_dir%/src/MessageHandler/*QueryHandler.php'
-            autoconfigure: false
-            tags:
-                - { name: messenger.message_handler, bus: query.bus }
+                # while those implementing QueryHandlerInterface will be
+                # registered on the query.bus bus
+                App\MessageHandler\QueryHandlerInterface:
+                    tags:
+                        - { name: messenger.message_handler, bus: query.bus }
 
     .. code-block:: xml
 
@@ -185,32 +185,45 @@ the correct tag:
                 https://symfony.com/schema/dic/services/services-1.0.xsd">
 
             <services>
-                <!-- command handlers -->
-                <prototype namespace="App\MessageHandler\" resource="%kernel.project_dir%/src/MessageHandler/*CommandHandler.php" autoconfigure="false">
+                <!-- ... -->
+
+                <!-- all services implementing the CommandHandlerInterface
+                     will be registered on the command.bus bus -->
+                <instanceof id="App\MessageHandler\CommandHandlerInterface">
                     <tag name="messenger.message_handler" bus="command.bus"/>
-                </prototype>
-                <!-- query handlers -->
-                <prototype namespace="App\MessageHandler\" resource="%kernel.project_dir%/src/MessageHandler/*QueryHandler.php" autoconfigure="false">
+                </instanceof>
+
+                <!-- while those implementing QueryHandlerInterface will be
+                     registered on the query.bus bus -->
+                <instanceof id="App\MessageHandler\QueryHandlerInterface">
                     <tag name="messenger.message_handler" bus="query.bus"/>
-                </prototype>
+                </instanceof>
             </services>
         </container>
 
     .. code-block:: php
 
         // config/services.php
+        namespace Symfony\Component\DependencyInjection\Loader\Configurator;
 
-        // Command handlers
-        $container->services()
-            ->load('App\MessageHandler\\', '%kernel.project_dir%/src/MessageHandler/*CommandHandler.php')
-            ->autoconfigure(false)
-            ->tag('messenger.message_handler', ['bus' => 'command.bus']);
+        use App\MessageHandler\CommandHandlerInterface;
+        use App\MessageHandler\QueryHandlerInterface;
 
-        // Query handlers
-        $container->services()
-            ->load('App\MessageHandler\\', '%kernel.project_dir%/src/MessageHandler/*QueryHandler.php')
-            ->autoconfigure(false)
-            ->tag('messenger.message_handler', ['bus' => 'query.bus']);
+        return function(ContainerConfigurator $configurator) {
+            $services = $configurator->services();
+
+            // ...
+
+            // all services implementing the CommandHandlerInterface
+            // will be registered on the command.bus bus
+            $services->instanceof(CommandHandlerInterface::class)
+                ->tag('messenger.message_handler', ['bus' => 'command.bus']);
+
+            // while those implementing QueryHandlerInterface will be
+            // registered on the query.bus bus
+            $services->instanceof(QueryHandlerInterface::class)
+                ->tag('messenger.message_handler', ['bus' => 'query.bus']);
+        };
 
 Debugging the Buses
 -------------------
diff --git a/service_container/tags.rst b/service_container/tags.rst
index 8bddd65c795..2f60f369b97 100644
--- a/service_container/tags.rst
+++ b/service_container/tags.rst
@@ -60,6 +60,8 @@ and many tags require additional arguments (beyond the ``name`` parameter).
 **For most users, this is all you need to know**. If you want to go further and
 learn how to create your own custom tags, keep reading.
 
+.. _di-instanceof:
+
 Autoconfiguring Tags
 --------------------