WordPress 4.6 Field Guide

Many of the changes in the forthcoming WordPress 4.6 are developer-focused changes that take place under the hood. Please remember to test your plugins, themes, and sites with WordPress 4.6 before the release. An hour of testing today can save you days of anguish later.

Enhanced Meta Registration

register_meta() is getting some updates to enable greater flexibility and features in the future (such as inclusion in the Rest API). Until now, register_meta() took four arguments. In WordPress 4.6, this will decrease to 3, with the third one being an array of arguments. When register_meta() is used with the old signature in WordPress 4.6, it will continue to function but will now return false. Please read the initial post outlining why register_meta() has been updated and the followup detailing further enhancements.

Persistent Comment Cache

Since WordPress 2.6, the comments API has purposefully not used a persistent cache. Over the past 20 releases, changes have been made to purge the problems from the comments API that caused this. If you have a plugin which modifies comment data directly please change them to make use of the various comment API functions or use clean_comment_cache(). You can hit this changes announcement for more info.

New Object: WP_Post_Type

Rather than a standard object, there is now a WP_Post_Type for each registered post type. Three functions and three actions have been changed to use this new object. WP_Post_Type provides methods to handle post type supports, rewrite rules, meta boxes, hooks, and taxonomies.

🛫 Open Sans, 🛬 Native Fonts

With the continued evolution of system fonts allowing for all devices to have a beautiful looking admin, WordPress 4.6 updates the font stack. To keep your custom admin pages looking consistent with the rest of the WordPress admin, you are encouraged to audit your CSS. The new font stack is:

font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen-Sans, Ubuntu, Cantarell, "Helvetica Neue", sans-serif;

When using this font stack, it must be called using the font-family property, and not the font shorthand. This works around an issue in Microsoft Edge. Additionally, the only font weights used in core now are 400 for general text and 600 for heavier text.

Shiny Updates

One of the user-facing features in 4.6 is an update to Shiny Updates, first introduced in 4.2. For developers, the change to pay attention to is that the JavaScript under the updates handle has been refactored and updated to support plugins and themes. If you are dependent on that handle, make sure to read about the shiny updates changes.

Resource Hints in 4.6

Resource Hints is a rather new W3C specification that “defines the dns-prefetch, preconnect, prefetch, and prerender relationships of the HTML Link Element (<link>)”. These can be used to assist the browser in the decision process of which origins it should connect to, and which resources it should fetch and preprocess to improve page performance.

In 4.6, WordPress adds an API to register and use resource hints. The relevant ticket is #34292.

Developers can use the wp_resource_hints filter to add custom domains and URLs for dns-prefetchpreconnect, prefetch or prerender. One needs to be careful to not add too many resource hints as they could quite easily negatively impact performance, especially on mobile.

WP_Term_Query

WordPress 4.6 will introduce WP_Term_Query. This new class brings parity between taxonomy term queries and WP’s other content type queries: WP_Query, WP_Comment_Query, and WP_User_Query. And – as in the case of posts, comments, and users – the get_terms() function has been converted to a wrapper for the new WP_Term_Query.

Internationalization

Everyone should be able to use WordPress in the language they want. WordPress 4.6 makes a number of changes to assist with internationalization and localization. Some of the highlights include:

  • Just-in-time loading for translations. You do not have to call load_plugin_textdomain() or load_theme_textdomain() anymore (if you distribute your theme/plugin via wordpress.org).
  • Community translations are now favored over translations which are included in your theme/plugin.
  • Localized jQuery UI datepicker.
  • Support for comment number declension in get_comments_number_text(). See #13651.
  • Fallback for TextDomain header field in get_plugin_data(). See #36706.
  • Updated list of continents and cities for the timezone selector. See #37554.
  • Support for the German (Switzerland) locale in remove_accents(). See #37076.
  • Improved support for month name declension. See #36790.

Pre-instantiated Widget Registration in 4.6

Since WP_Widget was introduced in 2.8 the register_widget() and unregister_widget() functions required the class name (string) of a WP_Widget subclass to be supplied. As of 4.6 these functions also accept a class instance (object) of a WP_Widget subclass as well. See #28216.

Two key benefits of allowing objects to be instantiated are:

  1. Widgets can now be instantiated and registered with constructor dependency injection.
  2. New widget types can now be added dynamically, such as adding a Recent Posts widget for each post type, per #35990.

New and Improved Customizer APIs

The customizer has four major changes in WordPress 4.6. The most prominent is a new collection of APIs for validation of setting values. Included in this new notifications API for the customizer.

Additional changes include some CSS cleanup. Custom controls that use part of the core UI and subclass WP_Customize_Media_Control no longer need to create their own CSS styles that duplicate core rules. Because the markup and styling have changed significantly, please test any custom controls, CSS, or JavaScript that is related to media controls in the customizer.

If your code uses the customizer, you are encouraged to review the changes.

Bootstrap/Load Updates in 4.6

Alert: A late change was made to <a href=”https://make.wordpress.org/core/2016/08/13/global-overloading-in-advanced-cache-php/”>remove protection for overloading Plugin API related global variables</a> in <code>advanced-cache.php</code>

Every time WordPress is loaded, it goes through the bootstrap or loading process. In WordPress 4.6, there will be a few changes to the process focused on making pieces available earlier. Many of these changes will have no effect whatsoever on the vast majority of WordPress sites. However, if you are the type that maintains your own advanced-cache.php drop-in, host/run large profile sites, or work on tools that bootstrap WordPress is odd ways, you need to know about the following changes:

  • Load plugin.php earlier in wp-settings.php
  • is_ssl() is now located in wp-includes/load.php
  • ABSPATH can now be safely defined before WordPress is loaded

Multisite Focused Changes

This release, work continues on multisite with a focus on improved APIs and performance. Some highlights include:

  • New WP_Site_Query and WP_Network_Query classes to query sites and networks in a standardized way.
  • Enhancements to WP_Site and WP_Network objects including lazy-loading for site details.
  • A new helper function get_current_network_id() to find the current network’s ID.
  • wp_get_sites() has been deprecated. get_site(), get_sites(), get_network(), and get_networks() are the future.

External Library Updates

  • Masonry was updated to version 3.3.2 from version 3.1.4.
  • imagesLoaded was updated to version 3.2.0 from version 3.1.4.
  • imagesLoaded can now be enqueued without Masonry being enqueued. For backward compatibility reasons, imagesLoaded remains a dependency for Masonry.
  • MediaElement.js was updated to version 2.22.0 from version 2.18.1.
  • TinyMCE was updated to version 4.4.1 from version 4.3.10.
  • Backbone.js was updated to version 1.3.3 from 1.2.3.

Summaries for each of these updates and links to full changelogs are available.

But Wait! There’s More!

Over 280 bugs, 125 enhancements, 7 feature requests, and 18 blessed tasks have been marked as fixed in WordPress 4.6. Some additional ones include:

Please, test your code. Fixing issues now, before the release, helps you and helps millions of WordPress sites.

#4-6, #dev-notes, #field-guide