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examples/middleware/README.md

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+# Middlewares
+
+## Type of middlewares in pyTelegramBotAPI
+Currently, synchronous version of pyTelegramBotAPI has two types of middlewares:
+
+- Class-based middlewares
+- Function-based middlewares
+
+## Purpose of middlewares
+Middlewares are designed to get update before handler's execution.
+
+## Class-based middlewares
+This type of middleware has more functionality compared to function-based one.
+
+Class based middleware should be instance of `telebot.handler_backends.BaseMiddleware.`
+
+Each middleware should have 2 main functions:
+
+`pre_process` -> is a method of class which receives update, and data.
+
+Data - is a dictionary, which could be passed right to handler, and `post_process` function.
+
+`post_process` -> is a function of class which receives update, data, and exception, that happened in handler. If handler was executed correctly - then exception will equal to None.
+
+## Function-based middlewares
+To use function-based middleware, you should set `apihelper.ENABLE_MIDDLEWARE = True`.
+This type of middleware is created by using a decorator for middleware.
+With this type middleware, you can retrieve update immediately after update came. You should set update_types as well.
+
+## Why class-based middlewares are better?
+- You can pass data between post, pre_process functions, and handler.
+- If there is an exception in handler, you will get exception parameter with exception class in post_process.
+- Has post_process -> method which works after the handler's execution.
+