Coding Standards Updates for PHP 5.6

With the minimum PHP version increasing to 5.6 as of WordPress 5.2, now’s a good time to be reviewing the WordPress Coding Standards.

Here is a set of changes that I’d like to propose.

Anonymous Functions (Closures)

Anonymous functions are a useful way to keep short logic blocks inline with a related function call. For example, this preg_replace_callback() call could be written like so:

$caption = preg_replace_callback(
	'/<[a-zA-Z0-9]+(?: [^<&gt;]+&gt;)*/',
	function ( $matches ) {
		return preg_replace( '/[\r\n\t]+/', ' ', $matches[0] );

This improves the readability of the codebase, as the developer doesn’t need to jump around the file to see what’s happening.

Coding Standards Proposal

Where the developer feels is appropriate, anonymous functions may be used as an alternative to creating new functions to pass as callbacks.

Anonymous functions must not be passed as filter or action callbacks in WordPress Core, as they cannot be removed by remove_action() / remove_filter() (see #46635 for a proposal to address this). Outside of Core, developers may pass anonymous functions as filter or action callbacks at their own discretion.


Namespaces are a neat way to encapsulate functionality, and are a common feature in modern PHP development practices. As we’ve discovered in the past, however, introducing namespaces to the WordPress codebase is a difficult problem, which will require careful architecture and implementation.

Side note: there’s currently no timeline for introducing namespaces to WordPress Core, expressions of interest are welcome. 🙂

Coding Standards Proposal

At this time, namespaces must not be used in WordPress Core.

Short Array Syntax

Rather than declaring arrays using the array( 1, 2, 3 ) syntax, they can now be shortened to [ 1, 2, 3 ]. This matches how arrays are declared in the WordPress JavaScript Coding Standards.

To allow for plugins and themes that support older versions of WordPress, I’d like to propose that WordPress Core switches to short array syntax immediately, but plugins and themes may choose which they use. A future iteration would make short array syntax a requirement.

Coding Standards Proposal

Arrays must be declared using short array syntax in WordPress Core. Arrays may be declared using short array syntax outside of Core.

Short Ternary Syntax

A fairly common pattern when setting a variable’s value looks something like this:

$a = $b ? $b : $c;

The short ternary syntax allows this to be shortened, like so:

$a = $b ?: $c;

It’s important to note that this is different to the null coalesce operator, which was added in PHP 7. If $b is undefined, the short ternary syntax will emit a notice.

Coding Standards Proposal

Short ternary syntax may be used where appropriate.

Assignments within conditionals

While this isn’t directly related to the PHP version bump, I’d like to propose disallowing assignments within conditionals. Particularly when there are multiple conditions, it can be quite difficult to spot assignments occurring in a conditional. This arguably falls under the Clever Code guidelines, but hasn’t been formalised.

For example, this if statement would be written like so:

$sticky_posts = get_option( 'sticky_posts' );
if ( 'post' === $post_type &amp;&amp; $sticky_posts ) {
	// ...

Coding Standards Proposal

Assignments within conditionals are not allowed.

Other New Features

Any other new features available in PHP 5.6 can be used, though we should continue to carefully consider their value and (in the case of newer PHP modules) availability on all hosts.

How do you feel about these changes? Are there other changes related to PHP 5.6 that you’d like to suggest?

#php, #wpcs

Dev Chat Summary: May 30th (4.9.7 week 2)

This post summarizes the dev chat meeting from May 30th (agenda, Slack archive).

4.9.7 planning

  • No pressing need for quick 4.9.7 release, so aiming for ~6-8 week release cycle for 4.9.7
  • Leads nominated so far: @sergeybiryukov able to help as deputy (e.g., committing, backporting); @danieltj, @desrosj, and @tristangemus open to help contribute during 4.9.7
  • Please comment on this post, ping @jeffpaul, or comment during the next dev chat for nominations (self or otherwise) for release leads on 4.9.7

Updates from focus leads and component maintainers

  • The PHP team posted a summary from their meeting last week covering the “Upgrade PHP” page and possible Gutenberg blocks. Please join them this coming Monday, June 4th at 15:00 UTC in #core-php
  • The GDPR Compliance team met earlier today and of note will be changing the Slack channel and post tags to Core Privacy this Friday, June 1st. Please join them next Wednesday, June 6th at 15:00 UTC in #core-privacy

Guidelines for fixing coding standard violations

  • Now that r42343 has landed, Core is accepting patches to fix coding standards (CS) violations. The meeting attendees agreed on the following guidelines:
    • Patches for any CS fixes are welcome, as long as they’re not so extensive that it would require refreshing an unreasonable amount of regular patches.
    • In order to avoid wasting time, patches for violations which cannot be automatically fixed by `phpcbf` should be given preference over ones that can be automatically fixed.
    • Regardless of many files are touched in a CS patch, the corresponding commits should be limited to fixing a single file in each commit.
    • CS patches should be treated just like any other patch, and reviewed critically before being committed. That also applies to any changes made by `phpcbf`.
    • Commits for new features, bug fixes, and other “logic” changes should not include unrelated CS fixes. Coding standards fixes should be done in a separate commit. If a line is already being changed to fix a bug, etc, then it should have CS violations fixed at the same time. If fixing the violation for that line would introduce changes beyond that line, though, then the CS fixes should be done in a separate commit.
  • Does anyone strongly object to those, before they’re added to Handbook?

General announcements

Next meeting

The next meeting will take place on June 6, 2018 at 20:00 UTC / June 6, 2018 at 20:00 UTC in the #core Slack channel. Please feel free to drop in with any updates or questions. If you have items to discuss but cannot make the meeting, please leave a comment on this post so that we can take them into account.

#4-9-7, #core, #core-php, #core-privacy, #dev-chat, #gdpr-compliance, #privacy, #summary, #wpcs

Dev Chat Agenda: May 30th (4.9.7 week 2)

This is the agenda for the weekly dev meeting on May 30, 2018 at 20:00 UTC / May 30, 2018 at 20:00 UTC:

If you have anything to propose to add to the agenda or specific items related to the above, please leave a comment below. See you there!

#4-9-7, #agenda, #core, #dev-chat, #wpcs