From: Bill Kelly <billk@...>
Date: 2005-09-10T03:44:20+09:00
Subject: Re: Embedding Ruby into C

From: "Dennis Schridde" <devurandom@gmx.net>

> But I think this is again very complex and it uses C++,
> what seems to make it relatively different from a plain C
> approach.

I haven't compiled the following - just cobbled it together
from other code that does run.  But maybe it will be of some
help?


#include "ruby.h"

static VALUE mFoo;

static VALUE foo_hello_world (VALUE self)
{
    printf("Hello! I'm a C function, called from Ruby.\n");
    return self;
}

int main (int argc, char **argv)
{
    // Initialize Ruby.......

#ifdef _WIN32
    // ruby win32 init
    NtInitialize(&argc, &argv);
#endif

    ruby_init();
    ruby_script("embedded");


    // define a new module "Foo" containing a method "hello_world"
    // which calls the C function foo_hello_world()
    mFoo = rb_define_module("Foo");
    rb_define_module_function(mFoo, "hello_world",
                              RUBY_METHOD_FUNC(foo_hello_world), 0);


    // load and execute a hypothetical "test.rb" which
    // can do whatever it wants - including call Foo.hello_world
    int status;
    rb_load_protect(rb_str_new2("test.rb"), 0, &status);
    if (status == 0) {
        int state = ruby_exec();
    }

    // TODO: example calling arbitrary Ruby method from C

    return 0;
}


I didn't provide an example of calling an arbitrary Ruby 
method from C.  I know it's easy, but I didn't have an example
handy.


Regards,

Bill