improving code design with readonly models

src/Envelope/Envelope.php

@@ -7,10 +7,10 @@
 
 final readonly class Envelope
 {
-    public object $message;
+    public Message $message;
     public Stamps $stamps;
 
-    public static function wrap(object $message, array $stamps = []): self
+    public static function wrap(Message $message, array $stamps = []): self
     {
         return new self($message, $stamps);
     }
@@ -28,7 +28,7 @@ public function unwrap(): mixed
         };
     }
 
-    private function __construct(object $message, array $stamps)
+    private function __construct(Message $message, array $stamps)
     {
         $this->message = $message;
         $this->stamps = new Stamps($stamps);

src/Envelope/Message.php

@@ -0,0 +1,7 @@
+<?php
+
+namespace OpenSolid\Bus\Envelope;
+
+readonly abstract class Message
+{
+}

src/Envelope/Stamp/HandledStamp.php

@@ -2,7 +2,7 @@
 
 namespace OpenSolid\Bus\Envelope\Stamp;
 
-final readonly class HandledStamp
+final readonly class HandledStamp extends Stamp
 {
     public function __construct(
         public mixed $result,

src/Envelope/Stamp/Stamp.php

@@ -0,0 +1,7 @@
+<?php
+
+namespace OpenSolid\Bus\Envelope\Stamp;
+
+readonly abstract class Stamp
+{
+}

src/Envelope/Stamp/Stamps.php

@@ -5,12 +5,12 @@
 final class Stamps implements \Countable
 {
     /**
-     * @param array<class-string, array<object>> $collection
+     * @param array<class-string, array<Stamp>> $collection
      */
     private array $collection = [];
 
     /**
-     * @param array<object> $stamps
+     * @param array<Stamp> $stamps
      */
     public function __construct(array $stamps = [])
     {
@@ -19,33 +19,33 @@ public function __construct(array $stamps = [])
         }
     }
 
-    public function add(object $stamp): self
+    public function add(Stamp $stamp): self
     {
         $this->collection[$stamp::class][] = $stamp;
 
         return $this;
     }
 
     /**
-     * @template T of object
+     * @template T of Stamp
      *
      * @param class-string<T> $class
      *
      * @return T|null
      */
-    public function first(string $class): ?object
+    public function first(string $class): ?Stamp
     {
         return $this->collection[$class][0] ?? null;
     }
 
     /**
-     * @template T of object
+     * @template T of Stamp
      *
      * @param class-string<T> $class
      *
      * @return T|null
      */
-    public function last(string $class): ?object
+    public function last(string $class): ?Stamp
     {
         if ([] === $stamps = $this->collection[$class] ?? []) {
             return null;
@@ -55,7 +55,7 @@ public function last(string $class): ?object
     }
 
     /**
-     * @template T of object
+     * @template T of Stamp
      *
      * @param class-string<T>   $class
      * @param \Closure(T): bool $fn
@@ -69,7 +69,7 @@ public function filter(string $class, \Closure $fn): self
     }
 
     /**
-     * @template T of object
+     * @template T of Stamp
      *
      * @param class-string<T>    $class
      * @param \Closure(T): mixed $fn

src/LazyMessageMessageBus.php

@@ -2,11 +2,13 @@
 
 namespace OpenSolid\Bus;
 
+use OpenSolid\Bus\Envelope\Message;
+
 /**
  * A bus responsible for dispatching messages lazily to their handlers.
  * The messages are stored in an internal queue and dispatched when the bus is flushed.
  */
 interface LazyMessageMessageBus extends MessageBus, FlushableMessageBus
 {
-    public function dispatch(object $message): null;
+    public function dispatch(Message $message): null;
 }

src/MessageBus.php

@@ -2,11 +2,13 @@
 
 namespace OpenSolid\Bus;
 
+use OpenSolid\Bus\Envelope\Message;
+
 /**
  * A bus responsible for dispatching messages to their handlers
  * and returning a result.
  */
 interface MessageBus
 {
-    public function dispatch(object $message): mixed;
+    public function dispatch(Message $message): mixed;
 }

src/NativeLazyMessageBus.php

@@ -2,6 +2,7 @@
 
 namespace OpenSolid\Bus;
 
+use OpenSolid\Bus\Envelope\Message;
 use Symfony\Contracts\Service\ResetInterface;
 
 final class NativeLazyMessageBus implements LazyMessageMessageBus, ResetInterface
@@ -13,7 +14,7 @@ public function __construct(
     ) {
     }
 
-    public function dispatch(object $message): null
+    public function dispatch(Message $message): null
     {
         $this->messages[] = $message;
 

src/NativeMessageBus.php

@@ -3,6 +3,7 @@
 namespace OpenSolid\Bus;
 
 use OpenSolid\Bus\Envelope\Envelope;
+use OpenSolid\Bus\Envelope\Message;
 use OpenSolid\Bus\Middleware\Middleware;
 use OpenSolid\Bus\Middleware\MiddlewareStack;
 
@@ -18,7 +19,7 @@ public function __construct(iterable $middlewares)
         $this->middlewares = new MiddlewareStack($middlewares);
     }
 
-    public function dispatch(object $message): mixed
+    public function dispatch(Message $message): mixed
     {
         $envelope = Envelope::wrap($message);
 

tests/Fixtures/MyMessage.php

@@ -2,6 +2,8 @@
 
 namespace OpenSolid\Tests\Bus\Fixtures;
 
-class MyMessage
+use OpenSolid\Bus\Envelope\Message;
+
+readonly class MyMessage extends Message
 {
 }