Multi language site using only .mo and WPLANG

Question

Hello world/ Bonjour le monde,

What technical limitations exist that would prevent the following from working (assume all static content with translations made in .mo file)

Pseudo code:

For every request:

• Check if query string contains field :myLang:
• If value of :myLang: equals "en_US"
• Then ~somehow change WPLANG to "en_Us"
  (Or force Wordpress to behave as if WPLANG was actually set to '')
• Else- serve request as French using the fr_FR.mo as defined in wp-config.php

I am vaguely aware that it has something to do with the way Wordpress is initialized. I know WPLANG can't be changed on the fly.

Answer 1

I am vaguely aware that it has something to do with the way Wordpress is initialized. I know WPLANG can't be changed on the fly.

It's how PHP works: You can't change an already defined constant.

But there're filters for that. The following plugin is a sketch that you could use and try to see if this direction fits your needs.

<?php
defined( 'ABSPATH' ) OR exit;
/**
 * Plugin Name: (#102471) Query Locale
 */

add_filter( 'locale', 'wpse_102471_locale', 20 );
/**
 * Callback to filter the locale/textdomain.
 * Assumes that you got a `lang` query var
 * @param  bool $locale
 * @return mixed string/bool $locale|$GLOBALS['wp_query']['lang']
 */
function wpse_102471_locale( $locale = false )
{
    global $wp_query;
    if ( isset( $wp_query['lang'] ) )
         return $wp_query['lang'];

    return $locale;
}