From: Alex Fenton <alex@...>
Date: 2008-12-12T01:48:07+09:00
Subject: Re: Q: FFI and C++?

Jeremy Henty wrote:
> On 2008-12-11, Jason Roelofs <jameskilton@gmail.com> wrote:
> 
>> Because of the  complexity that C++ adds, I  doubt that any feasible
>> FFI library can be made that works reliably against C++ libraries,
> 
> I was afraid of that.
> 
>> Rice - ...
>> Rb++ - ...
> 
> I looked at  those but I thought they were  targeted at generating MRI
> bindings.  The point of using FFI is to eliminate MRI-specific C code.
> I just need to wrap C++ with C to get functions that FFI can call, eg.

Latest SWIG does include C as a target language. In other words it can 
generate ANSI C wrapper code around C++ classes / libraries.

This was a Google Summer of Code project from this year and I believe 
it's only available from SVN, not in a released version.

http://swig.svn.sourceforge.net/viewvc/swig/branches/gsoc2008-maciekd/Doc/Manual/C.html


> I already know this works, now I'm trying to save effort, particularly
> with parsing C++  and autogenerating wrapper code.  Maybe  I could use
> rbgccxml and  add my  own XML  -> wrapper code  backend.  It  looks as
> though rbgccxml is  precisely the bit of rbplusplus  that I would want
> to reuse.

SWIG can also output a parse of C++ classes and methods to XML. But if 
this is all you want to do, probably the Rb++ route is better as it has 
existing Ruby classes for making use of the parse. I guess in theory you 
might also be able to generate the FFI code from this at the same time.

alex