load_theme_textdomain( string $domain, string|false $path = false ): bool
- Since
- 1.5.0, 4.6.0, 6.7.0
- Source
wp-includes/l10n.php:1082
Description
If the current locale exists as a .mo file in the theme's root directory, it will be included in the translated strings by the $domain.
The .mo files must be named based on the locale exactly.
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.
$pathstring|falseoptional- Path to the directory containing the .mo file.
Default false.Default:false
Return value
bool- True when textdomain is successfully loaded, false otherwise.
Performance profile
How much work a call to load_theme_textdomain() does, and what it touches: the algorithmic scaling, the Zend instruction count per call across PHP versions, the hooks it hands control to, and the core code that calls it. Measured from the compiled opcodes, not a stopwatch, so every number is identical on any machine running the same PHP version, and every function in core is ranked by cost.
- Cost class
- Trivial
- Scaling
- Constant
- Instructions
- 7–21
- Plugin surface
- None
- Called by
- 9
Touches nothing outside its own arguments.
No loop in the body: the same number of instructions runs whatever you pass in.
Executed per call on PHP 8.5, depending on the branch taken. The body compiles to 22.
Nothing here hands control to plugin code.
9 places in core call this, so the cost is paid more often than your own code shows.
What it touches
- hookthird-party callbacks
apply_filters()one call below load_theme_textdomain()
Further down the call graph this can also reach option, cache, serialize, transient and query. Those are the worst case, several calls deep and usually down an error path, not what a normal call pays.
What one call costs · 3 distinct outcomes
One number would be a lie: the work depends on which branch runs. These are every distinct cost load_theme_textdomain() can have, taken from its control-flow graph on PHP 8.5.
| When | Instructions | Calls it makes |
|---|---|---|
!is_string($domain) | 7 | none |
is_string($domain) | 14–18 | ->set_custom_path() |
is_string($domain) | 17–21 | get_template_directory(), ->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: 22 instructions, 7–21 executed per call, 4 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 · 1
- get_template_directory()Retrieves template directory path for the active theme.
Used by · 9
- WP_Theme::load_textdomain()Loads the theme's textdomain.
- load_child_theme_textdomain()Loads the child theme's translated strings.
- twentyeleven_setup()Set up theme defaults and registers support for various WordPress features.
- twentyfifteen_setup()Sets up theme defaults and registers support for various WordPress features.
- twentyfourteen_setup()Twenty Fourteen setup.
- twentysixteen_setup()Sets up theme defaults and registers support for various WordPress features.
- twentyten_setup()Set up theme defaults and registers support for various WordPress features.
- twentythirteen_setup()Twenty Thirteen setup.
- twentytwelve_setup()Twenty Twelve setup.
Source code
function load_theme_textdomain( $domain, $path = false ) { /** @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; } if ( ! $path ) { $path = get_template_directory(); } $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 1.5.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
About this page
- Parsed data
- Generated from the wordpress-develop 6.7.7 tag, from
src/wp-includes/l10n.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.