wppaste
WordPress

__( string $text, string $domain = 'default' ): string

Since
2.1.0
Source
wp-includes/l10n.php:305

Translate a string and return it with __(): looks up $text in a text domain and gives back the translation, or the original text when none exists. It returns rather than prints, so use it wherever you need the localized string as a value; _e() is the echoing counterpart.

Retrieves the translation of $text.

Description

If there is no translation, or the text domain isn't loaded, the original text is returned.

Compatibility

WordPress
since 2.1.0
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

$textstring
Text to translate.
$domainstringoptional
Text domain. Unique identifier for retrieving translated strings.
Default 'default'.Default: 'default'

Return value

string
Translated text.

Code examples

Every example is editable and runs in a real WordPress booted in your browser by WordPress Playground. Press Run, then edit the code: clicking away re-runs it. Nothing is sent anywhere until you do.

Use a translated string as a value

Reach for __() when the translated text feeds into another function or gets concatenated before output.

$label = __( 'Read more', 'myplugin' );

printf(
	'<a class="more-link" href="%s">%s</a>',
	esc_url( get_permalink() ),
	esc_html( $label )
);

Always pass a literal string, never a variable: translation tools extract strings from source statically, so __( $message, 'myplugin' ) produces nothing translators can see. The domain must match the one your plugin or theme loads.

Performance profile

How much work a call to __() 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

Executed per call on PHP 8.5. The body compiles to 7.

Plugin surface
None

Nothing here hands control to plugin code.

Called by
50

50 places in core call this, so the cost is paid more often than your own code shows.

What it touches

  • hookthird-party callbacksapply_filters()one call below __()

Further down the call graph this can also reach query, option, cache, serialize and transient. Those are the worst case, several calls deep and usually down an error path, not what a normal call pays.

What one call costs · 1 distinct outcome

One number would be a lie: the work depends on which branch runs. These are every distinct cost __() can have, taken from its control-flow graph on PHP 8.5.

WhenInstructionsCalls it makes
always7translate()

Across PHP versions

Compiles the same on PHP 7.4, 8.1, 8.2, 8.3, 8.4, 8.5 and 8.6-dev: 7 instructions, 7 executed per call, 0 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

Used by · 50

Show all 50

Source code

View on Trac View on GitHub 

function __( $text, $domain = 'default' ) {	return translate( $text, $domain );}

Changelog

Introduced in 2.1.0. 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.

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
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