WP_Locale_Switcher::switch_to_locale( string $locale, int|false $user_id = false ): bool

Compatibility

Present in every tracked release (6.7.7 to 7.1.0), and compiles on PHP 7.4 through 8.6-dev.

Parameters

$localestring

The locale to switch to.

$user_idint|falseoptional

User ID as context. Default false.Default: false

Return value

bool

True on success, false on failure.

Performance profile

How much work a call to WP_Locale_Switcher::switch_to_locale() 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

8–25

Executed per call on PHP 8.5, depending on the branch taken. The body compiles to 27.

Plugin surface

1 hook

Third-party callbacks on 'switch_locale' run inside this call, and their cost is not bounded by anything here.

Called by

1

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

What it touches

• hookthird-party callbacksdo_action()called directly

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 · 2 distinct outcomes

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

Hooks and filters fired · 1

One hook fires while WP_Locale_Switcher::switch_to_locale() runs, in this order:

1. 1
   do_action( switch_locale )actionline 98 (+23 into the body)

   Fires when the locale is switched.

Uses · 3

• determine_locale()Determines the current locale desired for the request.
• do_action()Calls the callback functions that have been added to an action hook.
• WP_Locale_Switcher::change_locale()Changes the site's locale to the given one.

Used by · 1

• WP_Locale_Switcher::switch_to_user_locale()Switches the translations according to the given user's locale.

Source code

View on Trac ↗View on GitHub ↗

75	public function switch_to_locale( $locale, $user_id = false ) {76		$current_locale = determine_locale();77		if ( $current_locale === $locale ) {78			return false;79		}80 81		if ( ! in_array( $locale, $this->available_languages, true ) ) {82			return false;83		}84 85		$this->stack[] = array( $locale, $user_id );86 87		$this->change_locale( $locale );88 89		/**90		 * Fires when the locale is switched.91		 *92		 * @since 4.7.093		 * @since 6.2.0 The `$user_id` parameter was added.94		 *95		 * @param string    $locale  The new locale.96		 * @param false|int $user_id User ID for context if available.97		 */98		do_action( 'switch_locale', $locale, $user_id );99 100		return true;101	}

Changelog

Introduced in 4.7.0. 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 7.0.4 tag, from src/wp-includes/class-wp-locale-switcher.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.

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