It is considered good practice to validate variables before using them. As using type declarations is still very rare in the WordPress world, parameters passed in to functions may not be of the variable type expected. Similarly, the type of variable returned by a filter Filters are one of the two types of Hooks https://codex.wordpress.org/Plugin_API/Hooks. They provide a way for functions to modify data of other functions. They are the counterpart to Actions. Unlike Actions, filters are meant to work in an isolated manner, and should never have side effects such as affecting global variables and output. may have changed due to incorrect usage of the filter by plugins or themes.
One particular situation which causes bugs often is counting something which isn’t countable. Proper variable validation can prevent those bugs.
In PHP The web scripting language in which WordPress is primarily architected. WordPress requires PHP 5.6.20 or higher 7.2, a warning was introduced when count() is used on an uncountable value. PHP 7.3 will introduce the function is_countable(), which will help prevent this warning by checking that the passed variable is actually countable (the RFC has passed the vote and the function has already been implemented and merged into PHP Core).
Using count() to detect if a value is iterable (able to be passed to a foreach() loop The Loop is PHP code used by WordPress to display posts. Using The Loop, WordPress processes each post to be displayed on the current page, and formats it according to how it matches specified criteria within The Loop tags. Any HTML or PHP code in the Loop will be processed on each post. https://codex.wordpress.org/The_Loop., for example), is also a common practice. However, this will also result in warnings when upgrading to PHP 7.2. In PHP 7.1, the is_iterable() function was introduced to help prevent these warnings.
To help WordPress Core Core is the set of software required to run WordPress. The Core Development Team builds WordPress., plugins, and themes be forwards compatible, a polyfill for each of these functions has been added in 4.9.6. When a site is not running a version of PHP that includes these functions, WordPress will automatically load these polyfills.
Checking A Value Is Countable
is_countable() was introduced in #43583.
Old Way
if ( count( $var ) > 0 ) {
// Do something.
}
New Way
if ( is_countable( $var ) && count( $var ) > 0 ) {
// Do something.
}
Checking A Value Is Iterable
is_iterable() was introduced in #43619.
Old Way
if ( count( $var ) > 0 ) {
foreach( $var as $key => $value) {
// Do something.
}
}
New Way
if ( is_iterable( $var ) ) {
foreach( $var as $key => $value) {
// Do something.
}
}
Updating Core
New tickets should be opened on Trac for instances in Core that would benefit from these new functions on a case by case basis. Since all instances of count() and foreach() should be verified, a meta Meta is a term that refers to the inside workings of a group. For us, this is the team that works on internal WordPress sites like WordCamp Central and Make WordPress. ticket Created for both bug reports and feature development on the bug tracker. has been opened to keep track of which files have been checked (#44123).
Want to learn how to write better conditions?
To better understand how variables behave in various PHP versions, how to write better conditions, and to improve variable validation, you may like the PHP Cheat Sheets website.
#4-9-6, #dev-notes
