From: Kevin Smith <kevinbsmith@...>
Date: 2001-11-30T02:40:47+09:00
Subject: [ruby-talk:26941] Interfacing to a C++ library (was: overload possible?)

--- ts <decoux@moulon.inra.fr> wrote:
> >>>>> "Y" == Yee Keat <ykphuah@netwxs.com.my> writes:
> 
> Y> Hehe, sorry, yeah, thats the package that I downloaded
> and played around with 
> Y> when I say I played around with Ruby/QT, but still it
> contains some 
> Y> complications and the two actually doesn't interface
> cleanly.
> 
>  You have another example in the interface to fltk

I was surprised at how difficult it was to write a clean
wrapper to a C++ library. It's not that Ruby itself makes
it hard. It's that you have two inheritance trees--one in
C++ and another in Ruby.

For example, you might have a C++ Widget, and Button which
inherits from Widget. Now on the Ruby side, you want a Ruby
Widget that inherits from the C++ Widget, and you want a
Ruby Button that inherits from the C++ Button, BUT ALSO
inherits from the Ruby Button.

At least with FLTK, this was necessary because we wanted
people to be able to extend the Ruby Widget class and have
it affect Ruby Button. But we also wanted the Ruby Button
event handler to be able to invoke 'super' and have it
route to the C++ Button default handler.

We discussed several possible ways to structure the code,
and internally it ended up being fairly weird. But, I think
we were able to hide the weirdness from people who just use
Ruby/FLTK. Hopefully, from the outside, it just works.

Kevin


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