From: David Balmain <dbalmain.ml@...>
Date: 2006-09-21T17:36:55+09:00
Subject: Re: Creating a reference to a ruby variable in a C extension

On 9/21/06, Christer Sandberg <chrsan@gmail.com> wrote:
> Vincent Fourmond wrote:
> > Hello !
> >
> >> Then later on I wan't to use it like this:
> >>
> >> void call(void)
> >> {
> >>   rb_funcall(ref, rb_intern("some_method"), 0, 0);
> >> }
> >
> >   How comes this function has no parameters ? Is it being called from
> > ruby, or only from C code ?
> >
>
> Thank you for the reply, I'll try to clear things up a bit and explain
> what I want to do.
>
> The function is just an example for the sake of making my question a bit
> clearer. The real functions I am using has parameters. Those functions
> such as the one above will only be called from C code.
>
> >
> >   I tend to think that using global variables is not a really good idea.
> >  We need a bit more context about what you want to do. Is it a class ?
> > Will it have several instances ?
> >
> >   In the latter case, have a look at rb_iv_get and rb_iv_set to get/set
> > instance variables of a class instance, something like
> >
> >   rb_iv_set(self, rb_intern("@variable"), arg); /* in init(...) */
> >
> >   and
> >
> >
> > rb_funcall(rb_iv_get(self,rb_intern("@variable")),rb_intern("some_method"),
> > 0, 0); /* in call */
> >
>
> Yes, I'm writing a tiny Ruby class in C that wraps and uses a bison/flex
> generated parser. The saved variable reference will be used for making
> calls on the ruby instance. When those calls are made self is long gone
> out of scope sice it's the parser who triggers the method call. The C
> Ruby class just acts as a proxy or adapter between the parser and the
> Ruby object.

Hi Christer,

Instead of saving it as a global variable, you could save it as a
class variable. See rb_cvar_[gs]et (defined in variable.c). Just an
idea.

Cheers,
Dave