From: "Iñaki Baz Castillo" <ibc@...>
Date: 2012-05-10T20:08:58+09:00
Subject: Re: How to use Data_Wrap_Struct to assign the DATA VALUE to an exsiting Ruby object?

2012/5/9 Eric Wong <normalperson@yhbt.net>:
> Ruby itself uses this idiom in some places:
>
>        DATA_PTR(self) = ptr;

Thanks Eric. I've taken a look to file.c in Ruby sources which uses
this stuf in functions rb_stat_init() and rb_stat_init_copy().
Unfortunatelly I get a segmentfault after using DATA_PTR(self)=ptr,
let me show what I do:


Ruby land:
---------------

sock = klass.allocate
sock.init_udp_socket bind_ip, bind_port



C land:
----------

VALUE MyModule_init_udp_socket(VALUE self, VALUE rb_bind_ip, VALUE rb_bind_port)
{
  [...]
  struct my_udp_cdata* cdata = ALLOC(struct my_udp_cdata);

  cdata->xxxx = xxxx;
  cdata->xxxx = xxxx;

  DATA_PTR(self) = cdata;

  [...]
  return self;
}


This still does NOT crash, but if after the C function I call to any
attribute reader of _sock_ or use sock.instance_variable_set(), then
it crashes.

Am I doing something wrong? Thanks a lot.





-- 
Iñaki Baz Castillo
<ibc@aliax.net>