From: Victor Shepelev <vshepelev@...>
Date: 2006-06-06T22:49:55+09:00
Subject: Re: Call rb_instance_eval from C code

From: why the lucky stiff [mailto:ruby-talk@whytheluckystiff.net]
Sent: Monday, June 05, 2006 11:40 PM
> On Tue, Jun 06, 2006 at 04:43:10AM +0900, Mauricio Fernandez wrote:
> > On Tue, Jun 06, 2006 at 04:12:14AM +0900, why the lucky stiff wrote:
> > >   rb_funcall(obj, rb_intern("instance_eval"), 1, proc);
> >
> > I don't think that will work: proc is not a String but a Proc
> (TypeError).
> >
> > See [ruby-talk:180647] and [ruby-talk:188958].
> 
> Ohhhh.  I guess define_method can take a proc, though.  Back to ye olde
> cloaker.
> Based on Guy's example:
> 
>   wagon$ cat a.c
>   #include <ruby.h>
> 
>   static VALUE
>   rb_proc_bind(VALUE obj, VALUE a)
>   {
>       VALUE meth, meta;
>       VALUE cloaker = ID2SYM(rb_intern("__cloaker__"));
>       meta = rb_singleton_class(obj);
>       rb_funcall(meta, rb_intern("define_method"), 2, cloaker, a);
>       meth = rb_funcall(meta, rb_intern("instance_method"), 1, cloaker);
>       rb_funcall(meta, rb_intern("remove_method"), 1, cloaker);
>       return rb_funcall(meth, rb_intern("bind"), 1, obj);
>   }
> 
>   VALUE
>   obj_eval_it(int argc, VALUE *argv, VALUE self)
>   {
>       VALUE meth, proc;
>       rb_scan_args(argc, argv, "0&", &proc);
> 
>       /* !^! here is your rb_instance_eval replacement, victor. !^! */
>       meth = rb_proc_bind(self, proc);
>       return rb_funcall(meth, rb_intern("call"), 0);
>   }
> 
>   void Init_a()
>   {
>       VALUE obj = rb_funcall(rb_cObject, rb_intern("new"), 0);
>       rb_define_method(rb_cObject, "eval_it", obj_eval_it, -1);
>       rb_const_set(rb_cObject, rb_intern("OBJ"), obj);
>   }
> 
>   wagon$ ruby -ra -e 'p Object::OBJ; Object::OBJ.eval_it { @b = 12 }; p
> Object::OBJ'
>   #<Object:0x80768dc>
>   #<Object:0x80768dc @b=12>
> 
> But now I really don't understand specific_eval().

Thanks why! Would try this.

Victor.