Recommendation for a C++ signals/actor framework

Question

I have the following requirements:

• A signal emitted from one thread can be landed on a slot from another thread. (cross-threaded) In case of actor model: a passed message from one actor (running on a separate thread, of course) can be received by another actor (pretty obvious I know).
• A signal can pass user defined data with it.
• Speed (should be very fast).
• Lightweight.
• Portable (target iOS).
• Easy to integrate into a project (preferably a single header file).
• Easy to use.

Basically, that's all. As you can see, the actor framework will fit as well (message passing instead of emitting a signal).

P.S. Why two minuses, People? :) Ohhhh very friendly, now it's 8 - that's better! :)

Answer 1

Boost.Signals2 is at least most of what you want: http://www.boost.org/doc/libs/release/doc/html/signals2.html