_wp_filter_build_unique_id( string $hook_name, callable $callback, int $priority ): string|null
- Since
- 2.2.3, 5.3.0, 6.9.0, 7.1.0
- Source
wp-includes/plugin.php:1002
Description
Functions and static method callbacks are just returned as strings and shouldn't have any speed penalty.
Compatibility
- WordPress
- since 7.1.0
- 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_namestring- Unused. The name of the filter to build ID for.
$callbackcallable- The callback to generate ID for. The callback may or may not exist.
$priorityint- Unused. The order in which the functions associated with a particular action are executed.
Return value
string|null- Unique function ID for usage as array key, or null if it couldn't be determined.
Performance profile
How much work a call to _wp_filter_build_unique_id() does, and what it touches: the algorithmic scaling, the Zend instruction count per call across PHP versions, the hooks it hands control to, and the core code that calls it. Measured from the compiled opcodes, not a stopwatch, so every number is identical on any machine running the same PHP version, and every function in core is ranked by cost.
- Cost class
- Trivial
- Scaling
- Constant
- Instructions
- 6–23
- Plugin surface
- None
- Called by
- 3
Touches nothing outside its own arguments.
No loop in the body: the same number of instructions runs whatever you pass in.
Executed per call on PHP 8.5, depending on the branch taken. The body compiles to 38.
Nothing here hands control to plugin code.
3 places in core call this, so the cost is paid more often than your own code shows.
What one call costs · 2 distinct outcomes
One number would be a lie: the work depends on which branch runs. These are every distinct cost _wp_filter_build_unique_id() can have, taken from its control-flow graph on PHP 8.5.
| When | Instructions | Calls it makes |
|---|---|---|
| always | 6–23 | none |
!is_string($callback) | 12–22 | spl_object_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: 38 instructions, 6–23 executed per call, 6 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.
Used by · 3
- WP_Hook::add_filter()Adds a callback function to a filter hook.
- WP_Hook::has_filter()Checks if a specific callback has been registered for this hook.
- WP_Hook::remove_filter()Removes a callback function from a filter hook.
Source code
function _wp_filter_build_unique_id( $hook_name, $callback, $priority ): ?string { if ( is_string( $callback ) ) { return $callback; } if ( is_object( $callback ) ) { return (string) spl_object_id( $callback ); } if ( ! isset( $callback[1] ) || ! is_string( $callback[1] ) ) { return null; } if ( is_object( $callback[0] ) ) { // Object class calling. return ( (string) spl_object_id( $callback[0] ) ) . $callback[1]; } elseif ( is_string( $callback[0] ) ) { // Static calling. return $callback[0] . '::' . $callback[1]; } return null;}Changelog
Introduced in 2.2.3. 2 changes between 6.7.7 and 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
$callback retyped from callable|string|array to callable.verified against sourcestring to string|null.verified against source$hook_name and $priority are no longer used, and no longer returns false, but can still return void for invalid callbacks.from the docblockAbout this page
- Parsed data
- Generated from the wordpress-develop 7.1.0 tag, from
src/wp-includes/plugin.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.