MDL-19756 Added a shortcut method to moodle_html_components: add_confirm_action($message). This adds the appropriate onclick event handler for a confirmation message and can be used on any component that gets prepared properly by a renderer function.

lib/deprecatedlib.php

@@ -2595,8 +2595,7 @@ function print_single_button($link, $options, $label='OK', $method='get', $notus
     $form->id = $formid;
 
     if ($jsconfirmmessage) {
-        $confirmaction = new component_action('click', 'confirm_dialog', array('message' => $jsconfirmmessage));
-        $form->button->add_action($confirmaction);
+        $form->button->add_confirm_action($jsconfirmmessage);
     }
 
     $output = $OUTPUT->button($form);

lib/outputcomponents.php

@@ -220,6 +220,16 @@ class moodle_html_component {
             $this->label->text = $text;
         }
     }
+
+    /**
+     * Shortcut for adding a JS confirm dialog when the component is clicked.
+     * The message must be a yes/no question.
+     * @param string $message The yes/no confirmation question. If "Yes" is clicked, the original action will occur.
+     * @return void
+     */
+    public function add_confirm_action($message) {
+        $this->add_action(new component_action('click', 'confirm_dialog', array('message' => $message)));
+    }
 }
 
 /// Components representing HTML elements