From: Christopher Thompson <cthompson@...>
Date: 2008-11-28T01:27:45+09:00
Subject: [ruby-core:20139] Re: Ruby class variable access from C

_why wrote:
> On Thu, Nov 27, 2008 at 04:49:32AM +0900, Christopher Thompson wrote:
>> I think I can get it by doing:
>> VALUE myvar = rb_eval_string("Myclass::myvar");
>> but surely there's a better way?  I'm thinking something like
>> rb_cvar_get() but that requires that I pass in a VALUE and all I have is
>> a string at this point, "Myclass".
> 
> If you create the class in your C extension, you'll get a VALUE
> back.
> 
>   VALUE cMyclass;
> 
>   void
>   Init_myext()
>   {
>     cMyclass = rb_define_class("Myclass", rb_cObject);
>   }
> 
>   VALUE
>   much_much_later(VALUE self)
>   {
>     VALUE myvar = rb_cvar_get(cMyclass, rb_intern("@@myvar"));
>   }
> 
> _why
> 

Ahh, but I'm not creating it in the C extension, for reasons that won't
be immediately obvious and possibly should be refactored.

Matz suggested rb_const_get and rb_eval_string.  rb_eval_string is what
I'm already doing, so I'll look into rb_const_get.  But thanks, your
approach would work for most sane extensions.  :)