How do I force something onto the heap? (need for libev)

[Mike Parker]

On 3/6/2012 2:01 PM, Mike Parker wrote:
> On 3/6/2012 1:55 PM, Mike Parker wrote:
>> On 3/6/2012 1:34 PM, Tyler Jameson Little wrote:
>>> I've been playing with libev in D lately, and I've run into a problem.
>>> I've been able to hack around it, but it'd like to find a better, more
>>> general solution. Here's a link to the code:
>>>
>>> https://github.com/beatgammit/fun-with-d/blob/master/libev/tcp_server.d
>>>
>>> The code is a basic TCP server that responds to connections in a
>>> non-blocking fashion. It's not perfect, and the current problem I'm
>>> trying to solve is how to get my Socket instance (from accept) to the
>>> handler. Since everything is asynchronous, and the return value of
>>> accept() will get lost (garbage collected, I think). When I try to get
>>> the address of it, the compiler complains that it's not an lvalue.
>>
>> Socket instance returned by accept won't be garbage collected (or lost)
>> as long as you have a reference to it active somewhere in your program.
>> It doesn't matter which thread. Just take the return value of accept and
>> pass it to your handler as is. As long as your handler holds on to the
>> reference, you're fine. No need to try and get the address, or hack
>> around it.
>
> Ah, sorry. Never mind. I misunderstood the problem.
>
> I suggest you keep an associative array of Sockets, using req.handle as
> a key. Then, your code becomes this:
>
> // The map
> Socket[socket_t] sockets;
>
> // in connection_cb
> auto req = server.accept();
> sockets[req.handle] = req;
>
> // then in socket_watcher_cb
> auto req = sockets[w.fd];
>
>
Alternatively:

struct Wrapper
{
  Socket s;
  this(Socket s)
  {
     this.s = s;
  }
}

// in connection_cb
auto req = server.accept();
auto wrapper = new Wrapper(req);

Then assign the wrapper instance to the data pointer you mentioned.