Add ImmutableObject trait

src/Utils/ImmutableObject.php

@@ -0,0 +1,23 @@
+<?php declare (strict_types = 1);
+
+namespace Wavevision\Utils;
+
+use Nette\SmartObject;
+
+trait ImmutableObject
+{
+
+	use SmartObject;
+
+	/**
+	 * @param mixed $value
+	 * @return static
+	 */
+	final protected function withMutation(string $property, $value)
+	{
+		$object = clone $this;
+		$object->$property = $value;
+		return $object;
+	}
+
+}

tests/UtilsTests/ImmutableObject.php

@@ -0,0 +1,29 @@
+<?php declare (strict_types = 1);
+
+namespace Wavevision\UtilsTests;
+
+use Wavevision\Utils;
+
+class ImmutableObject
+{
+
+	use Utils\ImmutableObject;
+
+	private string $prop;
+
+	public function __construct(string $prop)
+	{
+		$this->prop = $prop;
+	}
+
+	public function getProp(): string
+	{
+		return $this->prop;
+	}
+
+	public function withProp(string $prop): self
+	{
+		return $this->withMutation('prop', $prop);
+	}
+
+}

tests/UtilsTests/ImmutableObjectTest.php

@@ -0,0 +1,17 @@
+<?php declare (strict_types = 1);
+
+namespace Wavevision\UtilsTests;
+
+use PHPUnit\Framework\TestCase;
+
+class ImmutableObjectTest extends TestCase
+{
+
+	public function testWithMutation(): void
+	{
+		$object = new ImmutableObject('default');
+		$this->assertSame('default', $object->getProp());
+		$this->assertNotSame($object, $object->withProp('changed'));
+	}
+
+}