Hello Christophe, I'm a boost msm first time user and I'm attempting to pass an event to my msm that cannot be copied. This event contains a /unique_ptr/ and my goal is to eventually steal it and store it under my msm. However, even with no deferred events, events are /copied/ to an internal queue, in /boost::msm::back::state_machine::do_pre_msg_queue_helper/. I just wanted to know if there was any chance /process_event/ could be overloaded and accept rvalue-ref or if by design, it's absolutely mandatory to copy those events. Many thanks for your great library -- View this message in context: http://boost.2283326.n4.nabble.com/meta-state-machine-process-event-need-to-... Sent from the Boost - Users mailing list archive at Nabble.com.