Move daily emails into the blog page

source/_posts/2023-05-17.md

@@ -0,0 +1,34 @@
+---
+title: >
+  What is deprecated code?
+pubDate: 2023-05-17
+permalink: >-
+  daily/2023/05/17/what-is-deprecated-code
+tags:
+  - php
+  - drupal
+  - software-development
+---
+
+Deprecating code is a way of identifying code that will be removed in a future major version.
+
+For example, the `drupal_set_message()` function was deprecated in Drupal 8.5 and removed in Drupal 9 as the `messenger` service replaced it.
+
+Once it was deprecated, the function was changed to use the new service to avoid duplicating code and a message was added to notify Developers:
+
+```language-php
+function drupal_set_message($message = NULL, $type = 'status', $repeat = FALSE) {
+  @trigger_error('drupal_set_message() is deprecated in Drupal 8.5.0 and will be removed before Drupal 9.0.0. Use \Drupal\Core\Messenger\MessengerInterface::addMessage() instead. See https://www.drupal.org/node/2774931', E_USER_DEPRECATED);
+
+  $messenger = \Drupal::messenger();
+  if (isset($message)) {
+    $messenger->addMessage($message, $type, $repeat);
+  }
+
+  return $messenger->all();
+}
+```
+
+This approach means that code can be refactored without breaking backwards-compatibility and, to upgrade any custom code to be compatible with Drupal 9, any references to `drupal_set_message()` just needed to be updated to use the new Messenger service.
+
+No large rewrite needed!