[boost] [signals] making Assignable and CopyConstructable

In my program I need to store a map of signals, with an integer id corresponding to a signal in the map. Objects can request to be informed when another a specific message is emitted by connecting a member function to the signal in this map at the index corresponding to that message type. However, since boost::signal inherits noncopyable, it cannot be stored in a map. What are the reasons for signal being noncopyable, and is there any chance this could be changed in the future?