[cffi-devel] Re: translate-type-from-foreign

[Sean]

On Thu, 2007-04-12 at 17:40 +0100, Luis Oliveira wrote: 
> Hmm.  I tried to track this alleged removal, unsuccessfully. :-) Are you
> sure you didn't add that code yourself?  I can't find this code in
> either 0.9.0 or 0.9.1.

<cough> <cough>, good catch. I swear one day I'll learn not to change
source code residing in asdf-install/site/ .


> In any case, you bring up a good point, which I've mentioned before too:
>   <http://article.gmane.org/gmane.lisp.cffi.devel/1033>
> 
> Using the cffi-newtypes branch (which I hope to merge soon, since there
> haven't been any complaints, unless James has any objections), you could
> do something like this:
> 
>   (defcstruct %my-struct ...)
> 
>   (define-foreign-type my-struct-type ()
>     ()
>     (:actual-type %my-struct)
>     (:simple-parser my-struct))
> 
>   (defmethod translate-from-foreign (value (type my-struct-type)) ...)
>   (defmethod translate-to-foreign (value (type my-struct-type)) ...)
>   (defmethod free-translated-object (value (type my-struct-type) param) ...)
> 
> Now, perhaps defcstruct could take an option to define a type class thus
> avoiding the need to define a wrapper type.  Perhaps something like
> this?
> 
>   (defcstruct (my-struct :class my-struct-type)
>     ...)
> 
> Any comments?

Nice, this is exactly the kind of thing that I'm currently looking for.
What does the :simple-parser slot-option do?

I'm just wondering does this provide any value other than the ability to
define translations on c-structs? Not that this is the wrong way to do
it but it does seem like a large amount of work to enable translations.


Just my 2c though.


Cheers,
 Sean.

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