WP_Hook::has_filter( string $hook_name = '', callable|string|array|false $callback = false ): bool|int
- Since
- 4.7.0
- Source
wp-includes/class-wp-hook.php:227
Description
When using the $callback argument, this function may return a non-boolean value that evaluates to false (e.g. 0), so use the === operator for testing the return value.
Compatibility
- WordPress
- since 4.7.0
- PHP
- 7.4–8.6-dev
- 6.7.7
- 6.8.8
- 6.9.7
- 7.0.4
- 7.1.0
Present in every tracked release (6.7.7 to 7.1.0), and compiles on PHP 7.4 through 8.6-dev.
Parameters
$hook_namestringoptional- The name of the filter hook. Default empty.Default:
'' $callbackcallable|string|array|falseoptional- The callback to check for.
This method can be called unconditionally to speculatively check a callback that may or may not exist. Default false.Default:false
Return value
bool|int- If
$callbackis omitted, returns boolean for whether the hook has anything registered. When checking a specific function, the priority of that hook is returned, or false if the function is not attached.
Performance profile
How much work a call to WP_Hook::has_filter() does, and what it touches: the algorithmic scaling, the Zend instruction count per call across PHP versions, the hooks it hands control to, and the core code that calls it. Measured from the compiled opcodes, not a stopwatch, so every number is identical on any machine running the same PHP version, and every function in core is ranked by cost.
- Cost class
- Light
- Scaling
- Scales with input
- Instructions
- 7–19
- Plugin surface
- None
- Called by
- 0
Touches nothing outside its own arguments.
The body loops, so the work grows with what you pass in.
Executed per call on PHP 8.5, depending on the branch taken. The body compiles to 25.
Nothing here hands control to plugin code.
Nothing in core calls this; the cost is only what you spend yourself.
What one call costs · 2 distinct outcomes
One number would be a lie: the work depends on which branch runs. These are every distinct cost WP_Hook::has_filter() can have, taken from its control-flow graph on PHP 8.5.
| When | Instructions | Calls it makes |
|---|---|---|
$callback === false | 7 | ->has_filters() |
$callback !== false | 12–19 | _wp_filter_build_unique_id() |
Across PHP versions
Compiles the same on PHP 7.4, 8.1, 8.2, 8.3, 8.4, 8.5 and 8.6-dev: 25 instructions, 7–19 executed per call, 5 branches. The work does not change between versions.
An instruction is not a fixed amount of time, so a matching count is not necessarily the same speed; what it rules out is a difference in the work itself.
Uses · 2
- _wp_filter_build_unique_id()Builds a unique string ID for a hook callback function.
- WP_Hook::has_filters()Checks if any callbacks have been registered for this hook.
Source code
public function has_filter( $hook_name = '', $callback = false ) { if ( false === $callback ) { return $this->has_filters(); } $function_key = _wp_filter_build_unique_id( $hook_name, $callback, false ); if ( ! $function_key ) { return false; } foreach ( $this->callbacks as $priority => $callbacks ) { if ( isset( $callbacks[ $function_key ] ) ) { return $priority; } } return false; }Changelog
Introduced in 4.7.0. One change between 6.7.7 and 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
$priority added.verified against sourceAbout this page
- Parsed data
- Generated from the wordpress-develop 6.7.7 tag, from
src/wp-includes/class-wp-hook.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it. - Corrections
- Something wrong on this page? Report it and it gets fixed in the next regeneration.