[Cffi-devel] Callbacks & Lambdas

[FAU]

On Wed, 2014-11-05 at 09:16 +0000, Luís Oliveira wrote:
> On Wed, Nov 5, 2014 at 7:53 AM, FAU <fau at riseup.net> wrote:
> > Is there a reliable/portable way to have lambdas called as a callback
> > from a foreign C function?  I assume there's not though.
> 
> SBCL has an ALIEN-LAMBDA but, last time I checked, most Lisps don't
> have a similar feature.
> 
> 
> > I could imagine it could be simulated (by a dispatcher callback or
> > something) so I'm wondering if somebody has done something like that
> > before and may share insight into her/his design.
> 
> I know one of the GTK bindings did something like this, but it used
> some GTK-specific tricks. IIRC, callbacks were somehow associated
> with specific GTK objects, and so you could dispatch on those.
> 
> If you know the callback will be invoked within your foreign function
> call, a special variable might do the trick, but you'd have to define
> callbacks a priori for each and every combination of argument types.
> 
> I think you might be able to do this using libffi's closure API,
> though. (See cffi-libffi for inspiration on how to use libffi.) Do you
> feel like giving that a go?

Thanks for all the details.  I'll have a look at this.