Behavior of message_t::copy is unclear

[peterchen-cp]

message_t::copy is declared as

void copy(message_t &msg_)

• it is unclear which is the source and which is the destination.
  (looking into the documentation, this is the destination, and msg_ is the source.
• as I understand, msg_ isn't const, because the underlying zmq_msg_copy may need to modify the source's reference count.

If these observations are correct, I would suggest to rename the parameter to

void copy(message_t &source)

(can provide pull request, but I'm not sure if I'm missing some detail...)

[gummif]

That is correct. But according to the docs it's more like a move operation

The original content of 'dest', if any, shall be released.