From: "Simon Kröger" <SimonKroeger@...>
Date: 2006-03-11T20:10:30+09:00
Subject: Re: C++ DLL example

Hi Mark,

it's not that hard, your cpp file should/could look like this:

---------------------------------------------------------------------
#include "ruby.h"
#include <string>
#include <iostream>

using namespace std;

static void greet(const string& name) {
  cout << "Hello " << name << endl;
}

static VALUE rb_greet(VALUE self, VALUE name){
  greet(STR2CSTR(name));
  return Qnil;
}

void Init_RubyDll() {
  rb_define_global_function("greet", (VALUE(*)(ANYARGS))rb_greet, 1);
}
---------------------------------------------------------------------

Add this to a new dll project, add the path to ruby.h to the project
settings and link against msvcrt-ruby18.lib.

Finally you have to export the Init_XXX (XXX has to be equal to the name
of your Dll) function. I usually add a /EXPORT:Init_RubyDll to the
command line options of the linker.

After doing so i could execute

C:\>ruby -e "require 'RubyDll'; greet 'Mark '"
Hello Mark

Hope that helps.

cheers

Simon

p.s.: one gotcha left: The ruby in the one-click-installer is compiled
with vc6, linking to libs from another version might be risky.

Mark Volkmann schrieb:
> Can someone point me to a simple example of calling a C++ function from Ruby?
> I know how to do it with SWIG, but I'm trying to learn how to do it
> without SWIG.
> I'd like to do this under Windows and have the C++ code in a DLL.
> No Windows APIs will be invoked. I just want to do something simple in
> C++ like this
> 
> static void greet(const string& name) {
>   cout << "Hello " << name << endl;
> }
> 
> and invoke the greet function from Ruby.
> 
> I know how to build a DLL using VC++ 8.
> I suspect the issue is that I don't have the right setup in my .cpp file.
> 
> --
> R. Mark Volkmann
> Partner, Object Computing, Inc.
> 
>