From: Paul Brannan <pbrannan@...>
Date: 2004-04-01T00:18:53+09:00
Subject: Re: Ruby/DL and C++ libraries

On Fri, Mar 26, 2004 at 12:04:28PM +0900, Bheeshmar Redheendran wrote:
> I'm trying to use a C++ shared library from Ruby and wanted to use
> Ruby/DL to do it.  It seemed straightforward enough, but I can't seem
> to match the signature on the function I want to import.

You will run into a number of problems using Ruby/DL with C++ code:

  - C++ function names are mangled, but there is no standard for how
    this mangling is done.  You will need to mangle your function name
    in the same way as the C++ implementation on your platform does.

  - C++ exceptions are not compatible with Ruby exceptions.  If your C++
    code throws an exception, then your program will have undefined
    behavior (it will likely call abort()).

  - C++ objects have constructors and destructors, and Ruby/DL doesn't
    know how to deal with these.  So if your C++ code returns an object
    by value, you might be able to get Ruby to wrap it, but getting Ruby
    to destruct the object when it is no longer used is a different
    story.

  - C++ has references in addition to pointers.  Ruby/DL doesn't know
    how to deal with references, though I suspect they should work
    similar to pointers.

You are probably better off using swig instead.

Paul