How to interface with an API written in C++?

[Derek Haskin]

Hi,

Does any know how I would go about making calls to a set of APIs written in
C++

The reason is I want to use ruby to make direct calls to our source control
tool which is Harvest.

thanks
derek.

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[Piers Harding]

Hi - my only experience with this is with Perl, but I would take a guess
that the process should be similar (someone else my know better).

Basically you would create a normal C extension for Ruby, but ensure
that your symbols are externalised (extern "C" { ... }), and then use
the c++ compiler. Then create your subroutines as normal, and call out
to the C++ library functions (thatyou need to link in).
I've not tried it myself, but I would have thought that it could be made
to fly?

Cheers,

Piers Harding.

--
http://www.piersharding.com
http://search.cpan.org/~piers/

[Nikolai Weibull]

Derek Haskin, May 5:

> Does any know how I would go about making calls to a set of APIs
> written in C++

You could search the archives at http://ruby-talk.org/ before asking
these questions. Anyway, here are two links with information,
http://aeditor.rubyforge.org/ruby_cplusplus/index.html and
http://www.ruby-doc.org/docs/ProgrammingRuby/. The first is C++
specific, the second contains information relating to API interfacing in
general.

[cut disclaimer]

Do you really, and I mean really, need to include that disclaimer?,
nikolai

--
Nikolai Weibull: now available free of charge at http://bitwi.se/!
Born in Chicago, IL USA; currently residing in Gothenburg, Sweden.
main(){printf(&linux["\021%six\012\0"],(linux)["have"]+"fun"-97);}

[Piers Harding]

OK - but here is a way to roll your own:
take one C++ file called dohello.cpp:
extern "C" {
void Init_dohello(void);
}
#include <ruby.h>
#include <iostream>

using namespace std;

int cpp_hello()
{
cout << "Hello World!" << endl;
return 0;
}

static VALUE my_hello( ) {
cpp_hello();
return Qtrue;
}

void
Init_dohello(void) {
VALUE hello;
hello = rb_define_module("CPPHello");
rb_define_module_function(hello, "do_hello", ( VALUE (*)(...) ) my_hello, 0);
}

Take an extconf.rb file:
require 'mkmf'
have_library("stdc++")
create_makefile("dohello")

And a test.rb file:
require "dohello.so"
CPPHello.do_hello()

And stir to your liking :-)

P.S. this was done under Linux FC3 + Ruby 1.8.2

Cheers,

Piers Harding.

--
http://www.piersharding.com
http://raa.ruby-lang.org/search.rhtml?search=piers&search_target=owner
http://search.cpan.org/~piers/

[Nikolai Weibull]

Piers Harding, May 5:

> OK - but here is a way to roll your own:

⋮

I don't understand what this has to do with what I said,

[Piers Harding]

It continues the conversation.

You came up with one set of suggestions based around rubyembed, and
Swing. I just demonstrated that you can do it without that if you
prefer not to go down that path.

Cheers,

Piers Harding.

--

[Nikolai Weibull]

Piers Harding, May 5:

> It continues the conversation.

Ah, not very obvious when you push down what I was saying to the bottom
of your message. Perhaps cut out only the vital parts of my message,
paste them at the top, and then write your reply?

> You came up with one set of suggestions based around rubyembed, and
> Swing. I just demonstrated that you can do it without that if you
> prefer not to go down that path.

I assume you mean SWIG. Sure, that's a valid point; I've never really
liked SWIG myself,

[Gennady Bystritksy]

For a long time I've been doing C++/Ruby interfacing mannually. And
about 2 weeks ago I got to giving SWIG a try (version 1.3.24).

I was truelly amazed with what I got. It transforms your C++ classes
into Ruby classes practically seamlessly, even giving you opportunity to
adjust to naming conventions simply by edditing a SWIG interface file.
Included typemaps allow you, for example, return std::string from your
C++ method, and automatically gets converted and returned to the Ruby
world as Ruby string, without you doing a stir. Isn't it amazing? ;-)

However, you can still use ruby C API in your C++ methods if you need
it. In particular, I use it to implement iterator-like methods using
rb_is_block_given_p() and rb_yield and SWIG's SWIG_NewPointerObj(...)
function.

After throwing away tons of now unnecessary code, I am fully convinced
that SWIG is the way to go for C++/Ruby integration.

Gennady.

[Edgardo Hames]

On 5/5/05, Nikolai Weibull

<mailing-lis...@rawuncut.elitemail.org> wrote:
>
> [cut disclaimer]
>
> Do you really, and I mean really, need to include that disclaimer?,
> nikolai
>

Sometimes, those disclaimers are automatically added by the company
MTA and you have no way to avoid it.

Kind Regards,
Ed
--
Encontrá a "Tu psicópata favorito" http://tuxmaniac.blogspot.com

"Tener una amiga en Ginebra es como tener quinotos en almibar o uvas en ron."
"Programming is like sex... make one mistake, and support it the rest
of your life."
"Defeat is an accomplishment not even the best of us could achieve."

[Nikolai Weibull]

Edgardo Hames, May 6:

> Nikolai Weibull wrote:

> > [cut disclaimer]

> > Do you really, and I mean really, need to include that disclaimer?

> Sometimes, those disclaimers are automatically added by the company

> MTA and you have no way to avoid it.

That’s what the “and I mean really” nonessential clause was for,