>Let us consider following execution sequence: 

>1. "io_service" destructor calls "io_service::service::shutdown_service"; 

>2. documentation of "io_service::service::shutdown_service" says that it 
>should destroy all user defined handler objects. 

>Is it true that user defined handler objects may access to (e.g. post a 
>handler) that "io_service" being destroyed and therefore has not exist 

>Could You please also clarify me what does "user defined handler object" 
>really mean? 


Hi, Andrew
    For your 2nd question "user defined handler object", I supposed that the parameter for the io_service::post() which is kinda "user defined handler object".
    1st, it could be a handler like "bind(&fun, this, _1, _2)".