Drupal 8.0.0 beta 12. More info: https://www.drupal.org/node/2514176

core/modules/migrate/src/ProcessPluginBase.php

@@ -0,0 +1,53 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\ProcessPluginBase.
+ */
+
+namespace Drupal\migrate;
+
+use Drupal\Core\Plugin\PluginBase;
+use Drupal\migrate\Plugin\MigrateProcessInterface;
+
+/**
+ * The base class for all migrate process plugins.
+ *
+ * Migrate process plugins are taking a value and transform them. For example,
+ * transform a human provided name into a machine name, look up an identifier
+ * in a previous migration and so on.
+ *
+ * @see https://www.drupal.org/node/2129651
+ * @see \Drupal\migrate\Plugin\MigratePluginManager
+ * @see \Drupal\migrate\Plugin\MigrateProcessInterface
+ * @see \Drupal\migrate\Annotation\MigrateProcessPlugin
+ * @see plugin_api
+ *
+ * @ingroup migration
+ */
+abstract class ProcessPluginBase extends PluginBase implements MigrateProcessInterface {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function transform($value, MigrateExecutableInterface $migrate_executable, Row $row, $destination_property) {
+    // Do not call this method from children.
+    if (isset($this->configuration['method'])) {
+      if (method_exists($this, $this->configuration['method'])) {
+        return $this->{$this->configuration['method']}($value, $migrate_executable, $row, $destination_property);
+      }
+      throw new \BadMethodCallException(sprintf('The %s method does not exist in the %s plugin.', $this->configuration['method'], $this->pluginId));
+    }
+    else {
+      throw new \BadMethodCallException(sprintf('The "method" key in the plugin configuration must to be set for the %s plugin.', $this->pluginId));
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function multiple() {
+    return FALSE;
+  }
+
+}