It's no big deal ... but why can't you copy one of these?  Surely just increase the reference count and party?  

Did I miss something subtle?

TBH I didn't add a copy constructor because you don't actually need one - all instances of the class are effectively identical.

..but I guess it probably does need to be copyable so that you can use it as a member inside copyable objects, so I should add one!

Would have saved me at least 100 keypresses :) (And the possibility of cocking up my own copy constructor et al)