# Rb++ / rbgccxml 0.9.1

**URL:** <https://www.ruby-forum.com/t/rb-rbgccxml-0-9-1/180208>\
**Category:** Ruby\
**Created:** [December 14, 2009, 7:31pm UTC](https://www.ruby-forum.com/t/rb-rbgccxml-0-9-1/180208 "2009-12-14T19:31:15Z")\
**Posts on this page:** 5\
**Page:** 1

<div class="post-metadata">

**Author:** ![jruyle](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/d2c977/32.png) [@jruyle](https://www.ruby-forum.com/u/jruyle)\
**Post date:** [December 14, 2009, 7:31pm UTC](https://www.ruby-forum.com/t/rb-rbgccxml-0-9-1/180208/1 "2009-12-14T19:31:15Z")

</div>

What is rb++ / rbgccxml?

Rb++, rbgccxml, and rice compose a suite of tools that make wrapping  
C++  
libraries into  
Ruby extensions as simple as possible. This is built as a replacement  
for  
SWIG-Ruby.

What’s New

- Full 1.9 support through the entire stack!
- MinGW / MSYS build support on Windows.

rb++:  
\* Updated to work with the Rice::Director changes  
\* Fixed a bug where rb++ wasn’t using any superclass on classes with  
multiple superclasses  
\* Generated extension handles exceptions cleaner

```
* Various other small bug fixes and tweaks

```

rbgccxml:  
\* Switched parsing from libxml-ruby to nokogiri  
\* Fixed crash on encountering , but no real handling of the  
type  
yet.  
\* Fixed a bug with older gcc versions on dealing with anonymous  
enumerations

Project

Documentation: [http://rbplusplus.rubyforge.org](http://rbplusplus.rubyforge.org)

rb++: [GitHub - jameskilton/rbplusplus: Account name changed!](http://github.com/jameskilton/rbplusplus)  
rbgccxml: [GitHub - jameskilton/rbgccxml: Account name changed!](http://github.com/jameskilton/rbgccxml)

Installation

This single command will grab the whole stack needed for rb++ to work.

```
gem install rbplusplus

```

The stack includes four libraries: rb++, rbgccxml, gccxml\_gem, and  
rice

rb++

Rb++ makes it almost trivially easy to create Ruby extensions for C++  
library.  
In the simplest of cases, there is no need to ever touch C++,  
everything  
is done  
in a very simple and clean Ruby API.

rbgccxml

RbGCCXML allows one to easily parse out and query C / C++ code.  
This library uses GCC-XML to parse out the C / C++ code into XML, and  
then  
nokogiri  
to parse and query that XML.

gccxml\_gem

GCC-XML ([www.gccxml.org](http://www.gccxml.org)) is an application that takes takes the parse  
tree  
of C / C++  
and constructs a very parsable and queryable XML file with all related  
information.

This gem includes a binary build of GCC-XML for supported platforms,  
to make it trivially easy to install. Platforms currently supported  
are:

```
* Linux 32 & 64 bit
* Mac OS X
* Windows via MinGW / MSYS

```

Rice

The Ruby Interface for C++ Extensions, it provides a C++ API for  
working  
with ruby. More information  
available at its project page:

```
http://rice.rubyforge.org

```

Notes

Released under the MIT licence.

For those familiar with py++ / pygccxml, the similarities are in  
function  
only.  
Rb++ / rbgccxml were written from scratch to take advantage of the  
Ruby  
language to it’s fullest.

Bugs, patches, feature requests, et al should be posted to the  
corresponding project’s Issues page on github.

---

<div class="post-metadata">

**Author:** ![jruyle](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/d2c977/32.png) [@jruyle](https://www.ruby-forum.com/u/jruyle)\
**Post date:** [December 18, 2009, 3:06pm UTC](https://www.ruby-forum.com/t/rb-rbgccxml-0-9-1/180208/2 "2009-12-18T15:06:14Z")

</div>

Hi,

I seem to have something like a bug in rb++. For the case that I want to  
wrap a simple method  
the extension doesn’t compile because of multiple definitions. The issue  
is somewhat tricky since  
when I have a previously compiled extension and merely extend the header  
file, it compiles fine.  
Here test case:

wrapper.rb  
require ‘rubygems’  
require ‘rbplusplus’

include RbPlusPlus

Extension.new “test” do |ext|  
ext.sources ["/home/thor/rb++/test.hpp"]

ext.module “Test” do |mod|  
node = mod.namespace “T”  
end  
end

test.hpp  
#ifndef TEST  
#define TEST

#include

namespace T  
{

void test()  
{  
std::cout \<\< “i’m just sitting here” \<\< std::endl;  
}

}  
#endif

The error is encountered also if I have a class before the function  
test.

Thorsten

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<div class="post-metadata">

**Author:** ![jruyle](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/d2c977/32.png) [@jruyle](https://www.ruby-forum.com/u/jruyle)\
**Post date:** [December 18, 2009, 3:39pm UTC](https://www.ruby-forum.com/t/rb-rbgccxml-0-9-1/180208/3 "2009-12-18T15:39:01Z")

</div>

What you’re running into is a general C++ compilation issue when you  
have  
code in your header files. By default, rb++ writes out code in a  
one-file-per-class format, along with another file that’s the ruby  
extension  
starting point. Your test.hpp file ends up getting included into  
multiple  
files, and g++ doesn’t like it when it sees a fully defined method  
multiple  
times.

Two ways to deal with this:

1. Tell rb++ to write all code to single file:

ext.writer\_mode :single

1. Split your C++ code out:

test.hpp  
namespace T { void test(); }

test.cpp  
namespace T { void test() { … } }

Jason

---

<div class="post-metadata">

**Author:** ![jruyle](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/d2c977/32.png) [@jruyle](https://www.ruby-forum.com/u/jruyle)\
**Post date:** [December 22, 2009, 3:16pm UTC](https://www.ruby-forum.com/t/rb-rbgccxml-0-9-1/180208/4 "2009-12-22T15:16:38Z")

</div>

Sorry, I should have pointed you further towards the right answer. What  
you  
want is to have hpp + cpp (prototype in the hpp, implementation in the  
cpp)  
then you need to tell Rb++ to copy over the cpp file in with the  
generated  
sources so that it’s properly compiled and the linker can find the  
implementation of code defined in the hpp:

Extension.new “test” do |e|  
e.sources “test.hpp”, :include\_source\_files =\> “test.cpp”  
end

A more detailed example and definition is found in the tutorial:  
[http://rbplusplus.rubyforge.org/#source](http://rbplusplus.rubyforge.org/#source). Also please read the  
documentation  
on Extension#sources:  
[http://rbplusplus.rubyforge.org/rbplusplus/classes/RbPlusPlus/Extension.html#M000092](http://rbplusplus.rubyforge.org/rbplusplus/classes/RbPlusPlus/Extension.html#M000092)

Jason

---

<div class="post-metadata">

**Author:** ![jruyle](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/d2c977/32.png) [@jruyle](https://www.ruby-forum.com/u/jruyle)\
**Post date:** [December 22, 2009, 2:19pm UTC](https://www.ruby-forum.com/t/rb-rbgccxml-0-9-1/180208/5 "2009-12-22T14:19:51Z")

</div>

Well, actually it shouldn’t be included more than one time due  
to the header guard.  
But, you’re correct having method definitions in headers is not  
good style, so I decided to go the second route. Now ruby claims  
that the symbol test is undefined.  
Depending on the sources array, I get:  
hpp --\> undefined symbol  
hpp + cpp --\> double definition  
cpp --\> double definition  
I am doing something really stupid here, or is there a way to rb++  
to treat hpp + cpp as a package?

Thorsten