From: Norman Makoto Su <normsu@...>
Date: 2002-04-24T10:15:31+09:00
Subject: Re: building extensions-- new vs initialize

Hi, thanks for the reply.

> In general, redefinition of "new" will be deprecated in 1.8.

OK, I believe this will make things clearer.

> No, once defined a class, you can define class variables
> whenever.  Typically in the Init function, "new" is called for
> each object, however class variables are singleton.

Just to make sure I understand things, if I want to simulate the following in C:

class Foo
  @@bar = 1
end

Then, I have to define foo in a "new" method, right?  Since bar is part of the
class definition and should be initialized before an instance is even created.

Also, regarding the CD Player example, I guess what I'm trying to ask is why
can't I do this?  (instead of using new)

static VALUE
cd_init(VALUE self, VALUE unit)
{
  CDJukebox *ptr = CDPlayerNew(NUM2INT(unit));
  rb_iv_set(self, "@unit", unit);
  VALUE tdata = Data_Wrap_Struct(self, 0, cd_free, ptr);
  return tdata;
}

I suspect that its because tdata will be a class and not an object?  But, the
thing is, the below does work:

static VALUE
cd_init(VALUE self, VALUE unit)
{
  CDJukebox *ptr = CDPlayerNew(NUM2INT(unit));
  rb_iv_set(self, "@unit", unit);
  VALUE tdata = Data_Wrap_Struct(rb_cObject, 0, cd_free, ptr);
  rb_iv_set(self, "@jukebox", tdata);
  return self;
}

static VALUE
cd_seekTime(VALUE self)
{
  double tm;
  CDJukebox *ptr;
  Data_Get_Struct(rb_iv_get(self, "@jukebox"), CDJukebox, ptr);
  tm = CDPlayerAvgSeekTime(ptr);
  return rb_float_new(tm);
}

I don't get why the former doesn't work and the below does?  Well, any insight
would be helpful.

Thanks,

--
Norman