Issue #3311480: Remove the need of preprocess hooks: add_class & set_attributes

src/Definition/PatternDefinitionField.php

@@ -21,6 +21,8 @@ class PatternDefinitionField implements \ArrayAccess {
     'label' => NULL,
     'description' => NULL,
     'type' => NULL,
+    'add_class' => NULL,
+    'set_attribute' => NULL,
     'preview' => NULL,
     'escape' => TRUE,
     'additional' => [],
@@ -186,4 +188,24 @@ class PatternDefinitionField implements \ArrayAccess {
     return $this;
   }
 
+  /**
+   * Get classes to add to field value.
+   *
+   * @return array
+   *   Classes list.
+   */
+  public function getClassesToAdd() {
+    return $this->definition['add_class'];
+  }
+
+  /**
+   * Get attributes to set to field value.
+   *
+   * @return array
+   *   Attributes dict.
+   */
+  public function getAttributesToSet() {
+    return $this->definition['set_attribute'];
+  }
+
 }