Add simple abstract Attachment class

src/Attachment.php

@@ -0,0 +1,44 @@
+<?php
+declare(strict_types=1);
+
+namespace LotGD\Core;
+
+/**
+ * An attachment to a scene. This is desigend to be subclasses by modules to
+ * provide functinoality like forms or maybe image attachments to go along with a scene.
+ */
+abstract class Attachment
+{
+    protected $id;
+    protected $type;
+
+    /**
+     * Construct a new attachment of the given type. Randomly assigns it an ID.
+     * @param string $type Type of this attachment, in the vendor/module/type format.
+     * @return Attachment
+     */
+    public function __construct(string $type)
+    {
+        $this->id = bin2hex(random_bytes(8));
+        $this->type = $type;
+    }
+
+    /**
+     * Returns an unique identifier for this attachment. Each attachment instance
+     * will have its own unique ID, assigned at time of the instantiation.
+     * @return string
+     */
+    public function getId(): string
+    {
+        return $this->id;
+    }
+
+    /**
+     * Returns the type of this attachment, in vendor/module/type format.
+     * @return string
+     */
+    public function getType(): string
+    {
+        return $this->type;
+    }
+}