i18n: Define List item separator as a WP_Locale property.

The list item separator is a locale property, and it doesn't make much sense to translate it separately in multiple projects. This changeset implements the following modifications:

- Define list item separator as a new WP_Locale property
- Add `wp_get_list_item_separator()` as a wrapper for `WP_Locale::get_list_item_separator`
- Replace `$wp_locale->get_list_item_separator()` calls with `wp_get_list_item_separator()`
- Added a compatibility layer for bundled themes

Props SergeyBiryukov, swissspidy, rsiddharth, johnbillion, audrasjb.
Fixes #39733.


git-svn-id: https://develop.svn.wordpress.org/trunk@52929 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/class-wp-locale.php

@@ -95,6 +95,14 @@ class WP_Locale {
 	 */
 	public $number_format;
 
+	/**
+	 * The separator string used for localizing list item separator.
+	 *
+	 * @since 6.0.0
+	 * @var string
+	 */
+	public $list_item_separator;
+
 	/**
 	 * Constructor which calls helper methods to set up object variables.
 	 *
@@ -209,6 +217,9 @@ class WP_Locale {
 
 		$this->number_format['decimal_point'] = ( 'number_format_decimal_point' === $decimal_point ) ? '.' : $decimal_point;
 
+		/* translators: used between list items, there is a space after the comma */
+		$this->list_item_separator = __( ', ' );
+
 		// Set text direction.
 		if ( isset( $GLOBALS['text_direction'] ) ) {
 			$this->text_direction = $GLOBALS['text_direction'];
@@ -366,4 +377,15 @@ class WP_Locale {
 		/* translators: Localized date and time format, see https://www.php.net/manual/datetime.format.php */
 		__( 'F j, Y g:i a' );
 	}
+
+	/**
+	 * Retrieve the localized list item separator.
+	 *
+	 * @since 6.0.0
+	 *
+	 * @return string Localized list item separator.
+	 */
+	public function get_list_item_separator() {
+		return $this->list_item_separator;
+	}
 }

src/wp-includes/class-wp-theme.php

@@ -924,8 +924,7 @@ final class WP_Theme implements ArrayAccess {
 			case 'Tags':
 				static $comma = null;
 				if ( ! isset( $comma ) ) {
-					/* translators: Used between list items, there is a space after the comma. */
-					$comma = __( ', ' );
+					$comma = wp_get_list_item_separator();
 				}
 				$value = implode( $comma, $value );
 				break;

src/wp-includes/functions.php

@@ -8371,3 +8371,17 @@ function is_php_version_compatible( $required ) {
 function wp_fuzzy_number_match( $expected, $actual, $precision = 1 ) {
 	return abs( (float) $expected - (float) $actual ) <= $precision;
 }
+
+/**
+ * Retrieves the list item separator based on the locale.
+ *
+ * @since 6.0.0
+ *
+ * @global WP_Locale $wp_locale WordPress date and time locale object.
+ *
+ * @return string Locale specific list item separator.
+ */
+function wp_get_list_item_separator() {
+	global $wp_locale;
+	return $wp_locale->get_list_item_separator();
+}