From: Mark Volkmann <r.mark.volkmann@...>
Date: 2006-03-13T00:01:11+09:00
Subject: Re: C++ DLL example

Thanks for the detailed instructions Simon!

I'm trying to build my DLL with Visual C++ 2005 Express Edition which
is free. I saw your warning about the possibility that this won't work
because the one-click installer is compiled with VC6. I'm not able to
get to the point to test that though. I'm getting a compile error that
says win32.h needs windows.h and it can't find that. I searched my
entire hard drive for windows.h and only found one under my cygwin
directory. I don't want to use that one because I want to find a
solution that doesn't assume cygwin is installed. Any idea why it's
looking for windows.h and where it should be?

On 3/11/06, Simon Kr�ger <SimonKroeger@gmx.de> wrote:
> 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.
> >
> >
>
>
>


--
R. Mark Volkmann
Partner, Object Computing, Inc.