What's the reason of using auto self(shared_from_this()) variable in lambda function?

Question

I read the boost asio http server example code (see http://www.boost.org/doc/libs/1_54_0/doc/html/boost_asio/example/cpp11/http/server/connection.cpp) and find the auto self(shared_from_this()); variable is been used in the capture scope ([this, self]). But the self variable is not been used in the lambda function. Then what's the benefit of doing so?

Answer 1

This is done in order to make sure that connection object outlives the asynchronous operation: as long as the lambda is alive (i.e. the async. operation is in progress), the connection instance is alive as well.