Re: [Chicken-users] Chicken C interface

[Dan Leslie]

Thanks, I'll get on updating my broken eggs soon.

<obvious humpty dumpty joke notwithstanding>

-Dan

On 6/5/2013 2:39 PM, Felix wrote:
> From: "pluijzer ." <address@hidden>
> Subject: [Chicken-users] Chicken C interface
> Date: Wed, 5 Jun 2013 17:10:41 +0200
>
> > Hello everybody,
> >
> > I was planning to use Chicken Scheme in a fashion more similar to Guile and
> > Lua. i.e. passing Scheme Data Objects from Chicken to C and back using the
> > C interface.
> >
> > I am a little confused though as how to have a C function return a Scheme
> > List that is seen by the garbage collector.
> >
> > For example, is the code below correct, will the list be seen by the
> > garbage collector? And if not, is there correct way to do this.
> >
> > #>
> > C_word give_12()
> > {
> >    C_word *mem  = C_alloc(C_SIZEOF_LIST(2));
> >    C_word  list = C_list(&mem, 2, C_fix(1), C_fix(2));
> >    return list;
> > }
> > <#
> > (print ((foreign-lambda scheme-object "give_12")))
> As written in the other message: C_alloc is just a wrapper around alloca(3),
> so returning from the function invalidates or overwrites the data. A later
> (minor) garbage collection may actually recover the data, but it is not
> certain that it happens. See
>
>    http://api.call-cc.org/doc/foreign/access/foreign-primitive
>
> for a variant that allows stack-allocation.
>
>
> cheers,
> felix
>
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