[zeromq-dev] (no subject)

[Martin Sustrik]

Ilja, Andrew,

std::string is able to make the reference counting trasparent to the 
user using CoW semantics. Unfortunately, with zmq_msg_t we don't have 
this option.

The place where the abstraction leaks most is zmq_msg_close() function. 
It removes one reference from the BLOB (const operation) and if it 
reaches zero, it deletes the BLOB (non-const operation).

The most sensible option seems to be to treat close as non-const 
operation. The ugly part is the asymmetricity between zmq_msg_copy() 
which adds a reference and zmq_msg_close() which removes a reference. 
Former is const operation while later is non-const operation.

Another problem is getting a const data pointer from const message 
object. C doesn't support polymorphism so something like this is not 
possible:

     void *zmq_msg_data (zmq_msg_t *msg);
     const void *zmq_msg_data (const zmq_msg_t *msg);

Thoughts?
Martin