pointer to pointer in scala-native

Question

I'm trying to use czmq with scala-native and I haven't found a way to create pointer in scala-native.

here is extern:

@native.link("czmq")
@native.extern
object czmq {

//struct _zsock_t {
//    uint32_t tag;               //  Object tag for runtime detection
//    void *handle;               //  The libzmq socket handle
//    char *endpoint;             //  Last bound endpoint, if any
//    char *cache;                //  Holds last zsock_brecv strings
//    int type;                   //  Socket type
//    size_t cache_size;          //  Current size of cache
//    uint32_t routing_id;        //  Routing ID for server sockets
//};

  type zsock_t = native.CStruct7[
                                native.CUnsignedLongLong,
                                native.Ptr[Byte],
                                native.CString,
                                native.CString,
                                native.CInt,
                                native.CSize,
                                native.CUnsignedLongLong]

  def zsock_new_push(endpoint: native.CString): native.Ptr[zsock_t] = native.extern
  def zsock_new_pull(endpoint: native.CString): native.Ptr[zsock_t] = native.extern
  def zstr_send(dest: native.Ptr[Unit], str: native.CString): native.CInt = native.extern
  def zstr_recv(src: native.Ptr[Unit]): native.CString = native.extern
  //void zsock_destroy (zsock_t **self_p)
  def zsock_destroy(self_p: native.Ptr[native.Ptr[zsock_t]]):Unit = native.extern
}

and here is my simple main method:

object Main {
  def main(args: Array[String]): Unit ={
    val push = czmq.zsock_new_push(c"inproc://example")
    val pull = czmq.zsock_new_pull(c"inproc://example")
    czmq.zstr_send(push.cast[Ptr[Unit]], c"Hello World")  
    val s = fromCString(czmq.zstr_recv(pull.cast[Ptr[Unit]]))
    println("msg: "+s)
    czmq.zsock_destroy(push) // doesn't compile
    czmq.zsock_destroy(pull) // doesn't compile
  }
}

So the question is how to make push and pull variables pointers like in c with & ?

shem · Accepted Answer · 2017-05-08 03:23:21Z

2

I've reached out to scala-native team on gitter and the answer is to use stackalloc

val ppush = stackalloc[Ptr[czmq.zsock_t]]
val ppull = stackalloc[Ptr[czmq.zsock_t]]
!ppush = push
!ppull = pull
czmq.zsock_destroy(ppush)
czmq.zsock_destroy(ppull)

answered May 8, 2017 at 3:23

shem

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