sync middleware examples separated into two folders

examples/middleware/function_based/i18n.py

@@ -0,0 +1,53 @@
+#!/usr/bin/python
+
+# This example shows how to implement i18n (internationalization) l10n (localization) to create
+# multi-language bots with middleware handler.
+#
+# Note: For the sake of simplicity of this example no extra library is used. However, it is recommended to use
+# better i18n systems (gettext and etc) for handling multilingual translations.
+# This is not a working, production-ready sample and it is highly recommended not to use it in production.
+#
+# In this example let's imagine we want to introduce localization or internationalization into our project and
+# we need some global function to activate the language once and to use that language in all other message
+# handler functions for not repeatedly activating it.
+# The middleware (i18n and l10n) is explained:
+
+import telebot
+from telebot import apihelper
+
+apihelper.ENABLE_MIDDLEWARE = True
+
+TRANSLATIONS = {
+    'hello': {
+        'en': 'hello',
+        'ru': 'привет',
+        'uz': 'salom'
+    }
+}
+
+_lang = 'en'
+
+
+def activate(lang):
+    global _lang
+    _lang = lang
+
+
+def _(string):
+    return TRANSLATIONS[string][_lang]
+
+
+bot = telebot.TeleBot('TOKEN')
+
+
+@bot.middleware_handler(update_types=['message'])
+def activate_language(bot_instance, message):
+    activate(message.from_user.language_code)
+
+
+@bot.message_handler(commands=['start'])
+def start(message):
+    bot.send_message(message.chat.id, _('hello'))
+
+
+bot.infinity_polling()