From: Mr_Tibs <tiberiu.motoc@...>
Date: 2008-07-11T01:21:02+09:00
Subject: calling c++ from Ruby

Hi,

I wrote this question on the newsgroup yesterday, but I didn't see it
actually get posted. Here it goes again. I'm trying to call a c++
function from Ruby and I'm getting some errors compiling the c++
part.

Here is my code:
#include "ruby.h"
#include <iostream>
#include <stdarg.h>
VALUE MyTest = Qnil;
extern "C" VALUE create_project(char *c, ...)
{
        va_list args;
        va_start(args, c);
}
extern "C" void Init_mytest()
{
        MyTest = rb_define_module("MyTest");
        rb_define_method(MyTest, "create_project", &create_project,
1);
}

And here is the error:
MyTest.cpp: In function ‘void Init_mytest()’:
MyTest.cpp:16: error: invalid conversion from ‘VALUE (*)(char*, ...)’
to ‘VALUE (*)(...)’
MyTest.cpp:16: error:   initializing argument 3 of ‘void
rb_define_method(VALUE, const char*, VALUE (*)(...), int)’

If I don't put "char *c" in the arguments of create_project, it
compiles and works just fine. But if I don't have it, how can I get
the arguments?
I realize this is more of a c++ question, but if anyone has any
simple, fully working example of calling c++ code from Ruby, I would
like to see it.

Thanks,
Tiberiu