From: "Glenn M. Lewis" <glenn@...>
Date: 2002-11-22T01:30:21+09:00
Subject: Re: Questions about embedding Ruby in C

Johan Persson wrote:
> Or at least, is there any documentation aviable on the subject?
> 
> 

Hi Johan!

	I looked through a bunch of examples in the RAA, and here
is what I hacked together, and it seems to work... I'm just a newbie,
so take it all with a grain of salt...
							-- Glenn
=======================================================================

#include <ruby.h>
#include <stdio.h>

static VALUE defout_write(VALUE self, VALUE str)
{
   str = rb_obj_as_string(str);
   fprintf(stderr, "In defout_write: len=%d, str='%s'\n", RSTRING(str)->len, RSTRING(str)->ptr);
   rb_str_cat(self, RSTRING(str)->ptr, RSTRING(str)->len);
   return Qnil;
}

static VALUE defout_cancel(VALUE self)
{
   fprintf(stderr, "In defout_cancel\n");
   if (RSTRING(self)->len == 0) return Qnil;
   RSTRING(self)->len = 0;
   RSTRING(self)->ptr[0] = '\0';
   return Qnil;
}

static void init()
{
   ruby_init();
#if RUBY_VERSION_CODE >= 160
   ruby_init_loadpath();
#else
#if RUBY_VERSION_CODE >= 145
   rb_ary_push(rb_load_path, rb_str_new2("."));
#endif
#endif
   rb_defout = rb_str_new("", 0);
   rb_io_binmode(rb_stdout);	/* for mswin32 */
   rb_define_singleton_method(rb_defout, "write", (VALUE(*)(ANYARGS))&defout_write, 1);
   rb_define_singleton_method(rb_defout, "cancel", (VALUE(*)(ANYARGS))&defout_cancel, 0);
}

static void proc_args(int argc, char **argv)
{
   ruby_script(argv[0]);
   // Other stuff here for initializing FLTK...
}

int main(int argc, char **argv)
{
   // fprintf(stderr, "Calling init...\n");
   init();
   // fprintf(stderr, "Calling proc_args...\n");
   proc_args(argc, argv);
   // fprintf(stderr, "Calling run...\n");
   Fl::run();  // This is my FLTK GUI... you might not have this,
               // but you will need some kind of event loop or something.
               // Note that my GUI has callbacks that call 'ruby_eval', below...
   return 0;
}

VALUE ruby_eval(const char* str)
{
   int state = 0;
   fprintf(stderr, "Calling ruby: '%s'\n", str);
   VALUE val = rb_eval_string_protect(str, &state);
   if (state == Qundef) {
     fprintf(stderr, "ERROR: Undefined statement: '%s'\n", str);
   } else {
     fprintf(stderr, "State=%d, return VALUE=%08lX\n", state, val);
   }
   return val;
}