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WordPress

load_muplugin_textdomain( string $domain, string $mu_plugin_rel_path = '' ): bool

Since
3.0.0, 4.6.0, 6.7.0
Source
wp-includes/l10n.php:1042
Loads the translated strings for a plugin residing in the mu-plugins directory.

Compatibility

WordPress
since 6.7.0
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

$domainstring
Text domain. Unique identifier for retrieving translated strings.
$mu_plugin_rel_pathstringoptional
Relative to WPMU_PLUGIN_DIR directory in which the .mo file resides. Default empty string.Default: ''

Return value

bool
True when textdomain is successfully loaded, false otherwise.

Performance profile

How much work a call to load_muplugin_textdomain() 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

Touches nothing outside its own arguments.

Scaling
Constant

No loop in the body: the same number of instructions runs whatever you pass in.

Instructions
7–24

Executed per call on PHP 8.5, depending on the branch taken. The body compiles to 25.

Plugin surface
None

Nothing here hands control to plugin code.

Called by
0

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 load_muplugin_textdomain() can have, taken from its control-flow graph on PHP 8.5.

WhenInstructionsCalls it makes
!is_string($domain)7none
is_string($domain)20–24ltrim(), ->set_custom_path()

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, 7–24 executed per call, 3 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.

Source code

View on Trac View on GitHub 

function load_muplugin_textdomain( $domain, $mu_plugin_rel_path = '' ) {	/** @var WP_Textdomain_Registry $wp_textdomain_registry */	/** @var array<string, WP_Translations|NOOP_Translations> $l10n */	global $wp_textdomain_registry, $l10n; 	if ( ! is_string( $domain ) ) {		return false;	} 	$path = WPMU_PLUGIN_DIR . '/' . ltrim( $mu_plugin_rel_path, '/' ); 	$wp_textdomain_registry->set_custom_path( $domain, $path ); 	// If just-in-time loading was triggered before, reset the entry so it can be tried again.	if ( isset( $l10n[ $domain ] ) && $l10n[ $domain ] instanceof NOOP_Translations ) {		unset( $l10n[ $domain ] );	} 	return true;}

Changelog

Introduced in 3.0.0. Unchanged from 6.7.7 through 7.1.0.

  1. 6.7.7
  2. 6.8.8
  3. 6.9.7
  4. 7.0.4
  5. 7.1.0

Signature, return type and hooks compared across 5 parsed releases.

6.7.0
Translations are no longer immediately loaded, but handed off to the just-in-time loading mechanism.from the docblock
4.6.0
The function now tries to load the .mo file from the languages directory first.from the docblock
3.0.0
Introduced.from the docblock

About this page

Parsed data
Generated from the wordpress-develop 7.1.0 tag, from src/wp-includes/l10n.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.
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