[boost] [asio] wrapping handler with tuple in serialization example, client.cpp, connection.hpp

In svn, the serialization example wraps a mem func ptr in a tuple to be tossed through various bind calls. In client.cpp, I found that using boost::protect around the bind call prevents the compile errors but I'm not sure why. connection_.async_read(stocks_, boost::protect(boost::bind(&client::handle_read, this, boost::asio::placeholders::error))); Any ideas as to why this works?