replace trait with an abstract class

DavidBadura · DavidBadura · commit c0c486003cd5 · 2025-08-22T09:19:03.000+02:00
diff --git a/docs/pages/dynamic_consistency_boundary.md b/docs/pages/dynamic_consistency_boundary.md
@@ -92,13 +92,13 @@ Course exists:
 
 ```php
 use Patchlevel\EventSourcing\Attribute\Apply;
-use Patchlevel\EventSourcing\DCB\EventRouter;
+use Patchlevel\EventSourcing\DCB\BasicProjection;
 use Patchlevel\EventSourcing\DCB\Projection;
 
 /** @implements Projection<bool> */
 final class CourseExists implements Projection
 {
-    use EventRouter;
+    use BasicProjection;
 
     public function __construct(private readonly CourseId $courseId) {}
 
@@ -125,12 +125,12 @@ Current capacity of a course:
 
 ```php
 use Patchlevel\EventSourcing\Attribute\Apply;
-use Patchlevel\EventSourcing\DCB\EventRouter;
+use Patchlevel\EventSourcing\DCB\BasicProjection;
 use Patchlevel\EventSourcing\DCB\Projection;
 
 final class CourseCapacityProjection implements Projection
 {
-    use EventRouter;
+    use BasicProjection;
 
     public function __construct(private readonly CourseId $courseId) {}
 
@@ -163,12 +163,12 @@ Count subscriptions of a course:
 
 ```php
 use Patchlevel\EventSourcing\Attribute\Apply;
-use Patchlevel\EventSourcing\DCB\EventRouter;
+use Patchlevel\EventSourcing\DCB\BasicProjection;
 use Patchlevel\EventSourcing\DCB\Projection;
 
 final class NumberOfCourseSubscriptionsProjection implements Projection
 {
-    use EventRouter;
+    use BasicProjection;
 
     public function __construct(private readonly CourseId $courseId) {}
 
@@ -195,12 +195,12 @@ Count subscriptions of a student:
 
 ```php
 use Patchlevel\EventSourcing\Attribute\Apply;
-use Patchlevel\EventSourcing\DCB\EventRouter;
+use Patchlevel\EventSourcing\DCB\BasicProjection;
 use Patchlevel\EventSourcing\DCB\Projection;
 
 final class NumberOfStudentSubscriptionsProjection implements Projection
 {
-    use EventRouter;
+    use BasicProjection;
 
     public function __construct(private readonly StudentId $studentId) {}
 
@@ -227,13 +227,13 @@ Has the student already subscribed to this course:
 
 ```php
 use Patchlevel\EventSourcing\Attribute\Apply;
-use Patchlevel\EventSourcing\DCB\EventRouter;
+use Patchlevel\EventSourcing\DCB\BasicProjection;
 use Patchlevel\EventSourcing\DCB\Projection;
 
 /** @implements Projection<bool> */
 final class StudentAlreadySubscribedProjection implements Projection
 {
-    use EventRouter;
+    use BasicProjection;
 
     public function __construct(
         private readonly StudentId $studentId,
@@ -266,12 +266,12 @@ Next invoice number from the last event only:
 
 ```php
 use Patchlevel\EventSourcing\Attribute\Apply;
-use Patchlevel\EventSourcing\DCB\EventRouter;
+use Patchlevel\EventSourcing\DCB\BasicProjection;
 use Patchlevel\EventSourcing\DCB\Projection;
 
 final class NextInvoiceNumberProjection implements Projection
 {
-    use EventRouter;
+    use BasicProjection;
 
     public function initialState(): int
     {
diff --git a/src/DCB/BasicProjection.php b/src/DCB/BasicProjection.php
@@ -21,14 +21,19 @@
 
 /**
  * @experimental
- * @require-implements Projection
  * @template S = mixed
+ * @implements Projection<S>
  */
-trait EventRouter
+abstract class BasicProjection implements Projection, SubQueryProvider
 {
     /** @var array<class-string, string>|null $applyMethods */
     private array|null $applyMethods = null;
 
+    /**
+     * @param S $state
+     *
+     * @return S
+     */
     public function apply(mixed $state, Message $message): mixed
     {
         if (!$this->subQuery()->match($message)) {
@@ -57,7 +62,7 @@ public function subQuery(): SubQuery
     }
 
     /** @return list<class-string> */
-    public function eventTypeFilter(): array
+    protected function eventTypeFilter(): array
     {
         return array_keys($this->applyMethods());
     }
@@ -177,14 +182,14 @@ static function (ReflectionNamedType|ReflectionIntersectionType $reflectionType)
     }
 
     /** @return list<string> */
-    abstract public function tagFilter(): array;
+    abstract protected function tagFilter(): array;
 
-    public function streamName(): string|null
+    protected function streamName(): string|null
     {
         return null;
     }
 
-    public function lastEventIsEnough(): bool
+    protected function lastEventIsEnough(): bool
     {
         return false;
     }
diff --git a/src/DCB/CompositeProjection.php b/src/DCB/CompositeProjection.php
@@ -6,6 +6,7 @@
 
 use Patchlevel\EventSourcing\Message\Message;
 use Patchlevel\EventSourcing\Store\Query;
+use Patchlevel\EventSourcing\Store\SubQuery;
 
 use function array_map;
 
@@ -20,12 +21,19 @@ public function __construct(
 
     public function query(): Query
     {
-        $query = new Query(
-            ...array_map(
-                static fn (Projection $projection) => $projection->subQuery(),
-                $this->projections,
-            ),
-        );
+        $subQueries = [];
+
+        foreach ($this->projections as $projection) {
+            if ($projection instanceof SubQueryProvider) {
+                $subQueries[] = $projection->subQuery();
+
+                continue;
+            }
+
+            $subQueries[] = new SubQuery();
+        }
+
+        $query = new Query(...$subQueries);
 
         return $query->optimize();
     }
diff --git a/src/DCB/Projection.php b/src/DCB/Projection.php
@@ -5,7 +5,6 @@
 namespace Patchlevel\EventSourcing\DCB;
 
 use Patchlevel\EventSourcing\Message\Message;
-use Patchlevel\EventSourcing\Store\SubQuery;
 
 /**
  * @experimental
@@ -22,6 +21,4 @@ public function initialState(): mixed;
      * @return S
      */
     public function apply(mixed $state, Message $message): mixed;
-
-    public function subQuery(): SubQuery;
 }
diff --git a/src/DCB/SubQueryProvider.php b/src/DCB/SubQueryProvider.php
@@ -0,0 +1,13 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Patchlevel\EventSourcing\DCB;
+
+use Patchlevel\EventSourcing\Store\SubQuery;
+
+/** @experimental */
+interface SubQueryProvider
+{
+    public function subQuery(): SubQuery;
+}
diff --git a/tests/Integration/DynamicConsistencyBoundary/Course/Projection/CourseCapacityProjection.php b/tests/Integration/DynamicConsistencyBoundary/Course/Projection/CourseCapacityProjection.php
@@ -5,16 +5,13 @@
 namespace Patchlevel\EventSourcing\Tests\Integration\DynamicConsistencyBoundary\Course\Projection;
 
 use Patchlevel\EventSourcing\Attribute\Apply;
-use Patchlevel\EventSourcing\DCB\EventRouter;
-use Patchlevel\EventSourcing\DCB\Projection;
+use Patchlevel\EventSourcing\DCB\BasicProjection;
 use Patchlevel\EventSourcing\Tests\Integration\DynamicConsistencyBoundary\Course\CourseId;
 use Patchlevel\EventSourcing\Tests\Integration\DynamicConsistencyBoundary\Course\Event\CourseCapacityChanged;
 use Patchlevel\EventSourcing\Tests\Integration\DynamicConsistencyBoundary\Course\Event\CourseDefined;
 
-final class CourseCapacityProjection implements Projection
+final class CourseCapacityProjection extends BasicProjection
 {
-    use EventRouter;
-
     public function __construct(
         private readonly CourseId $courseId,
     ) {
diff --git a/tests/Integration/DynamicConsistencyBoundary/Course/Projection/CourseExists.php b/tests/Integration/DynamicConsistencyBoundary/Course/Projection/CourseExists.php
@@ -5,16 +5,13 @@
 namespace Patchlevel\EventSourcing\Tests\Integration\DynamicConsistencyBoundary\Course\Projection;
 
 use Patchlevel\EventSourcing\Attribute\Apply;
-use Patchlevel\EventSourcing\DCB\EventRouter;
-use Patchlevel\EventSourcing\DCB\Projection;
+use Patchlevel\EventSourcing\DCB\BasicProjection;
 use Patchlevel\EventSourcing\Tests\Integration\DynamicConsistencyBoundary\Course\CourseId;
 use Patchlevel\EventSourcing\Tests\Integration\DynamicConsistencyBoundary\Course\Event\CourseDefined;
 
-/** @implements Projection<bool> */
-final class CourseExists implements Projection
+/** @extends BasicProjection<bool> */
+final class CourseExists extends BasicProjection
 {
-    use EventRouter;
-
     public function __construct(
         private readonly CourseId $courseId,
     ) {
diff --git a/tests/Integration/DynamicConsistencyBoundary/Course/Projection/NumberOfCourseSubscriptionsProjection.php b/tests/Integration/DynamicConsistencyBoundary/Course/Projection/NumberOfCourseSubscriptionsProjection.php
@@ -5,15 +5,12 @@
 namespace Patchlevel\EventSourcing\Tests\Integration\DynamicConsistencyBoundary\Course\Projection;
 
 use Patchlevel\EventSourcing\Attribute\Apply;
-use Patchlevel\EventSourcing\DCB\EventRouter;
-use Patchlevel\EventSourcing\DCB\Projection;
+use Patchlevel\EventSourcing\DCB\BasicProjection;
 use Patchlevel\EventSourcing\Tests\Integration\DynamicConsistencyBoundary\Course\CourseId;
 use Patchlevel\EventSourcing\Tests\Integration\DynamicConsistencyBoundary\Course\Event\StudentSubscribedToCourse;
 
-final class NumberOfCourseSubscriptionsProjection implements Projection
+final class NumberOfCourseSubscriptionsProjection extends BasicProjection
 {
-    use EventRouter;
-
     public function __construct(
         private readonly CourseId $courseId,
     ) {
diff --git a/tests/Integration/DynamicConsistencyBoundary/Course/Projection/NumberOfStudentSubscriptionsProjection.php b/tests/Integration/DynamicConsistencyBoundary/Course/Projection/NumberOfStudentSubscriptionsProjection.php
@@ -5,15 +5,12 @@
 namespace Patchlevel\EventSourcing\Tests\Integration\DynamicConsistencyBoundary\Course\Projection;
 
 use Patchlevel\EventSourcing\Attribute\Apply;
-use Patchlevel\EventSourcing\DCB\EventRouter;
-use Patchlevel\EventSourcing\DCB\Projection;
+use Patchlevel\EventSourcing\DCB\BasicProjection;
 use Patchlevel\EventSourcing\Tests\Integration\DynamicConsistencyBoundary\Course\Event\StudentSubscribedToCourse;
 use Patchlevel\EventSourcing\Tests\Integration\DynamicConsistencyBoundary\Course\StudentId;
 
-final class NumberOfStudentSubscriptionsProjection implements Projection
+final class NumberOfStudentSubscriptionsProjection extends BasicProjection
 {
-    use EventRouter;
-
     public function __construct(
         private readonly StudentId $studentId,
     ) {
diff --git a/tests/Integration/DynamicConsistencyBoundary/Course/Projection/StudentAlreadySubscribedProjection.php b/tests/Integration/DynamicConsistencyBoundary/Course/Projection/StudentAlreadySubscribedProjection.php
@@ -5,16 +5,13 @@
 namespace Patchlevel\EventSourcing\Tests\Integration\DynamicConsistencyBoundary\Course\Projection;
 
 use Patchlevel\EventSourcing\Attribute\Apply;
-use Patchlevel\EventSourcing\DCB\EventRouter;
-use Patchlevel\EventSourcing\DCB\Projection;
+use Patchlevel\EventSourcing\DCB\BasicProjection;
 use Patchlevel\EventSourcing\Tests\Integration\DynamicConsistencyBoundary\Course\CourseId;
 use Patchlevel\EventSourcing\Tests\Integration\DynamicConsistencyBoundary\Course\Event\StudentSubscribedToCourse;
 use Patchlevel\EventSourcing\Tests\Integration\DynamicConsistencyBoundary\Course\StudentId;
 
-final class StudentAlreadySubscribedProjection implements Projection
+final class StudentAlreadySubscribedProjection extends BasicProjection
 {
-    use EventRouter;
-
     public function __construct(
         private readonly StudentId $studentId,
         private readonly CourseId $courseId,
diff --git a/tests/Integration/DynamicConsistencyBoundary/Invoice/Projection/NextInvoiceNumberProjection.php b/tests/Integration/DynamicConsistencyBoundary/Invoice/Projection/NextInvoiceNumberProjection.php
@@ -5,14 +5,11 @@
 namespace Patchlevel\EventSourcing\Tests\Integration\DynamicConsistencyBoundary\Invoice\Projection;
 
 use Patchlevel\EventSourcing\Attribute\Apply;
-use Patchlevel\EventSourcing\DCB\EventRouter;
-use Patchlevel\EventSourcing\DCB\Projection;
+use Patchlevel\EventSourcing\DCB\BasicProjection;
 use Patchlevel\EventSourcing\Tests\Integration\DynamicConsistencyBoundary\Invoice\Event\InvoiceCreated;
 
-final class NextInvoiceNumberProjection implements Projection
+final class NextInvoiceNumberProjection extends BasicProjection
 {
-    use EventRouter;
-
     /** @return list<string> */
     public function tagFilter(): array
     {
diff --git a/tests/Unit/Fixture/IncrementProjection.php b/tests/Unit/Fixture/IncrementProjection.php
@@ -5,13 +5,10 @@
 namespace Patchlevel\EventSourcing\Tests\Unit\Fixture;
 
 use Patchlevel\EventSourcing\Attribute\Apply;
-use Patchlevel\EventSourcing\DCB\EventRouter;
-use Patchlevel\EventSourcing\DCB\Projection;
+use Patchlevel\EventSourcing\DCB\BasicProjection;
 
-final class IncrementProjection implements Projection
+final class IncrementProjection extends BasicProjection
 {
-    use EventRouter;
-
     /** @param list<string> $tags */
     public function __construct(
         private readonly int $initial,

Original file line number	Diff line number	Diff line change
`@@ -21,14 +21,19 @@`
`21`	`21`
`22`	`22`	`/**`
`23`	`23`	`* @experimental`
`24`		`- * @require-implements Projection`
`25`	`24`	`* @template S = mixed`
	`25`	`+ * @implements Projection<S>`
`26`	`26`	`*/`
`27`		`-trait EventRouter`
	`27`	`+abstract class BasicProjection implements Projection, SubQueryProvider`
`28`	`28`	`{`
`29`	`29`	`/** @var array<class-string, string>\|null $applyMethods */`
`30`	`30`	`private array\|null $applyMethods = null;`
`31`	`31`
	`32`	`+ /**`
	`33`	`+ * @param S $state`
	`34`	`+ *`
	`35`	`+ * @return S`
	`36`	`+ */`
`32`	`37`	`public function apply(mixed $state, Message $message): mixed`
`33`	`38`	`{`
`34`	`39`	`if (!$this->subQuery()->match($message)) {`
`@@ -57,7 +62,7 @@ public function subQuery(): SubQuery`
`57`	`62`	`}`
`58`	`63`
`59`	`64`	`/** @return list<class-string> */`
`60`		`- public function eventTypeFilter(): array`
	`65`	`+ protected function eventTypeFilter(): array`
`61`	`66`	`{`
`62`	`67`	`return array_keys($this->applyMethods());`
`63`	`68`	`}`
`@@ -177,14 +182,14 @@ static function (ReflectionNamedType\|ReflectionIntersectionType $reflectionType)`
`177`	`182`	`}`
`178`	`183`
`179`	`184`	`/** @return list<string> */`
`180`		`- abstract public function tagFilter(): array;`
	`185`	`+ abstract protected function tagFilter(): array;`
`181`	`186`
`182`		`- public function streamName(): string\|null`
	`187`	`+ protected function streamName(): string\|null`
`183`	`188`	`{`
`184`	`189`	`return null;`
`185`	`190`	`}`
`186`	`191`
`187`		`- public function lastEventIsEnough(): bool`
	`192`	`+ protected function lastEventIsEnough(): bool`
`188`	`193`	`{`
`189`	`194`	`return false;`
`190`	`195`	`}`