[cffi-devel] Converting foreign structures with CFFI generic functions

[Liam Healy]

On Sun, Aug 28, 2011 at 4:41 AM, Luís Oliveira <luismbo at gmail.com> wrote:

> What kind of macro are you thinking of? In the COMPLEX case, do you
> want to abstract away the need to allocate (and free) the structure
> object explicitly?
>

I've written a macro define-structure-conversion to flesh out what I see as
the way to go.  Eventually, I think this would be best as a couple of key
arguments in the defcstruct, similar to FSBV's current :constructor and
:deconstructor arguments.

I am stuck however on recursive conversion of slots.  What I have works for
the complex example, but if I built on that with a  "real-and-complex"
structure and try to convert to foreign, I get an error because the complex
slot is already converted by the time it gets in the setf.  Even with an
existing pointer, as would be obtained from foreign-slot-pointer, the only
function I have at my disposal for translating the slot is
translate-to-foreign which creates a new foreign struct, it does not write
to an existing struct.  It seems I need something like a setf function.

See the define-structure-conversion definition and test case
examples<https://github.com/cffi/cffi/blob/4d475077a6c00dd12aa0fc72f8b36b8cb5b8c3d3/src/structures.lisp>.
Any thoughts on how to proceed?

Liam



>
> --
> Luís Oliveira
> http://r42.eu/~luis/
>
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