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

[deadalnix]

Le 06/03/2012 05:34, Tyler Jameson Little a écrit :
> 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.
>
> As you can see, I've hacked around it by grabbing the handle and
> recreating the Socket instance in the handler (line 14). The problem,
> however, is that this can only assume a single type in AddressFamily.
> Honestly, I will probably only need INET, INET6, or UNIX (which can be
> set in a global), but this sounds a bit hacky to me.
>
> I was able to hack around the problem for libev structs, because
> creating a new instance returns a pointer, which can be assigned
> somewhere else to be garbage collected later. This doesn't seem to be
> the case for classes, however.
>
> Initially, I solved this before by having a global Socket[] and adding
> sockets to it as I received them, but this was an even worse hack to get
> around the GC (see previous version in version control if interested).
> This did, however, allow me to get a reference from the array to assign
> to the data value (a void*), where it could be retrieved in the callback.
>
> Are there any other options that I've missed that would make this
> cleaner and more general?
>
> Also, I'd be interested if someone notices some badness in my code that
> could lead to nasty side-effects. I'm trying to make this example pretty
> robust in terms of cleaning up after myself and doing things correctly.
>
> Thanks so much!!

You can new stuff();

Alternatively, if you have of stuff passed by value, you can :

new stuff(stuffByValue); // Don't always work.

*([stuffByValue].ptr); // Crazy but works :D