[GUI] Example: Binding C++ to Haskell using the ffi

[Seth Kurtzberg]

The C++ compilers are all supposed to use the same name mangling scheme, which 
is part of the standard.

On Saturday 01 March 2003 03:11 pm, Daan Leijen wrote:
> On Sat, 1 Mar 2003 13:40:42 -0800 (PST), David Sankel <camio at yahoo.com> 
wrote:
> > Has any though gone into cplusplus?  If so, how would
> > it interface?  Would stubs on the c++ side be
> > generated or would it use the code directly.
>
> I think that it is in general infeasable to call c++ member
> function directly as different c++ compilers use wildly different
> calling conventions and name-mangling schemes. It makes more sense
> to call C++ via extern "C" wrappers and use foreign import ccall on
> the Haskell side.
>
> In my opinion, the 'ideal' way of interfacing to C++, or C, would
> be an adoption of H/Direct to read C or C++ header files directly
> and translating it to a default IDL specification -- one should
> than be able to augment this specification with IDL attributes,
> much like the current 'asf' files of H/Direct but probably more friendly.
> H/Direct could than generate both exern "C" wrappers and Haskell
> marshalling code at the same time.
>
> On the other hand, even though the above approach would solve all
> the interface problems once and for all, it certainly involves a
> significant amount of work to extend H/Direct with a C++ front-end and
> better asf support.
>
> All the best,
> 	Daan.
>
>
> ps. I have been experimenting with interfacing to the wxWindows
> library, a large C++ framework. I have used an existing Eiffel library
> that wrapped the C++ classes in C functions together with a small
> hand-written tool to translate their (simple) header files to Haskell
> marshalling code -- a poor-mans solution until H/Direct gets an update :-)
> It works rather well and imports 400 classes with 2500 methods with
> very reasonable type signatures. You may want to look at it to get some
> inspiration for interfacing to C++: http://wxhaskell.sourceforge.net
> It also shows how you can use polymorphism to mimic inheritance
> relationships (as described in "Calling hell from heaven and heaven
> from hell")
> pps. This is just a preview, don't expect a wxHaskell too soon, I have
> a thesis to finish in the next weeks :-)
>
> > Later,
> >
> > David J. Sankel
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>
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-- 
Seth Kurtzberg
M. I. S. Corp.
480-661-1849
seth at cql.com