FFI and callbacks (was: RE: How Do You Do Business Apps?)

John W. Sarkela john_sarkela at 4thEstate.com
Wed Mar 1 17:21:02 UTC 2000

Yikes... it seems like the Squeak world (or is it San Diego) is
caught in some kind of chronosynclastic infundibulum. :-)

We have a working callback mechanism based on POSIX-compliant
semaphores that we are preparing for release.  It is fully
synchronous now, but we are planning on support for asynchronous
call-in (to Squeak) as well.

We are preparing a VM plug-in that provides this mechanism through a .so on
Unixesque systems.  It is easy to see how Mac and Windows-32 ports may be
made.  There is a little bit of portable C-code to operate the platform
semaphore mechanisms.  The rest is in Smalltalk 'Slang' and regular
Smalltalk.  We have tested an implementation that used additional
primitives in the VM.  We are reimplementing these as a
named-primitive plugin.

We are planning to make this available by the time of Camp Smalltalk, but
may be able to post something sooner.

We have posted this notice because we are seeing a good number of calls for
this capability.  We can serve as the center for this effort if the
community is receptive.  We would like to advance this in the context of a
generalized message capability.

speaking on behalf of the technical staff at TFEI

John Sarkela
CTO The Fourth Estate, Inc.

> From: Gerardo Richarte <core.lists.squeak at core-sdi.com>
> Organization: Core-SDI, Buenos Aires, Argentina
> Reply-To: squeak at cs.uiuc.edu
> Date: 28 Feb 2000 13:32:37 -0300
> To: squeak at cs.uiuc.edu
> Subject: Re: FFI and callbacks (was: RE: How Do You Do Business Apps?)
> Resent-From: squeak at cs.uiuc.edu
> Resent-Date: 28 Feb 2000 16:39:39 -0000
> "Raab, Andreas" wrote:
>> Callbacks are currently not support in the FFI stuff. There is more than one
>> reason for it but for me the primary reason is that adding callbacks has
>> some serious implications on the general working of the VM - so I was trying
>> to avoid an (in my understanding unnecessary) complication for the
>> forthcoming J3.
> A while ago a thought of a portable way of implementing something like
> callbacks. Indeed I just realized how it's implemented in Squeak.
> Isn't it possible to provide a portable callback mechanism using Semaphores?
> Callbacker Bye!
> Richie++
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