Code review

includes/admin.form.inc

@@ -27,6 +27,11 @@ function islandora_repository_admin(array $form, array &$form_state) {
   $map_to_title = function ($backend) {
     return $backend['title'];
   };
+  // In case the selected breadcrumb backend is no longer available.
+  $breadcrumb_backend = variable_get('islandora_breadcrumbs_backends', ISLANDORA_BREADCRUMB_LEGACY_BACKEND);
+  if (!isset($breadcrumb_backend_options[$breadcrumb_backend])) {
+    $breadcrumb_backend = ISLANDORA_BREADCRUMB_LEGACY_BACKEND;
+  }
 
   $form = array(
     'islandora_tabs' => array(
@@ -107,7 +112,7 @@ function islandora_repository_admin(array $form, array &$form_state) {
           '#type' => 'radios',
           '#title' => t('Breadcrumb generation'),
           '#description' => t('How breadcrumbs for Islandora objects are generated for display.'),
-          '#default_value' => variable_get('islandora_breadcrumbs_backends', ISLANDORA_BREADCRUMB_LEGACY_BACKEND),
+          '#default_value' => $breadcrumb_backend,
           '#options' => array_map($map_to_title, $breadcrumb_backend_options),
           '#states' => array(
             'visible' => array(

includes/breadcrumb.inc

@@ -25,11 +25,13 @@
  *   drupal_set_breadcrumb().
  */
 function islandora_get_breadcrumbs(AbstractObject $object) {
+  $breadcrumbs = array();
   if (variable_get('islandora_render_drupal_breadcrumbs', TRUE)) {
     $backend = variable_get('islandora_breadcrumbs_backends', ISLANDORA_BREADCRUMB_LEGACY_BACKEND);
     $backends = module_invoke_all('islandora_breadcrumbs_backends');
     if ($backend === ISLANDORA_BREADCRUMB_LEGACY_BACKEND || !isset($backends[$backend])) {
       $breadcrumbs = islandora_get_breadcrumbs_recursive($object->id, $object->repository);
+      array_pop($breadcrumbs);
     }
     else {
       if (isset($backends[$backend]['file'])) {
@@ -37,7 +39,6 @@ function islandora_get_breadcrumbs(AbstractObject $object) {
       }
       $breadcrumbs = call_user_func($backends[$backend]['callable'], $object);
     }
-    array_pop($breadcrumbs);
     $context = 'islandora';
     drupal_alter('islandora_breadcrumbs', $breadcrumbs, $context, $object);
   }

islandora.api.php

@@ -911,7 +911,7 @@ function hook_islandora_repository_connection_construction_alter(RepositoryConne
 /**
  * Allow a overridable backend for generating breadcrumbs.
  *
- * Stolen shamelessly from @adam-vessey
+ * Stolen shamelessly from @adam-vessey.
  *
  * @return array
  *   Should return an associative array mapping unique (module-prefixed,
@@ -922,25 +922,21 @@ function hook_islandora_repository_connection_construction_alter(RepositoryConne
  *   - file: An optional file to load before attempting to call the callable.
  */
 function hook_islandora_breadcrumbs_backends() {
-  $a_callable = function ($object) {
-    // Do something to get an array of breadcrumb links for $object, root first.
-    return array($root_link, $collection_link, $object_link);
-  };
   return array(
     'awesome_backend' => array(
       'title' => t('Awesome Backend'),
-      'callable' => $a_callable,
+      'callable' => callback_islandora_breadcrumbs_backends($object),
     ),
   );
 }
 
 /**
- * Generate an array of links for breadcrumbs leading to $object, root level first.
+ * Generate an array of links for breadcrumbs leading to $object, root first.
  *
- * Stolen shamelessly from @adam-vessey
+ * Stolen shamelessly from @adam-vessey.
  *
  * @param AbstractObject $object
- *   The object to generate breadcrumbs for
+ *   The object to generate breadcrumbs for.
  *
  * @return array
  *   Array of links from root to $object.