Proof of concept dynamic FFI

Proof of concept dynamic FFI

[Jon Wilson]

Hi,
I've written a bit of code that lets you call any function from a 
dynamically loaded shared lib with any args.  Well, actually, since it 
is just a proof of concept, it only lets you call functions that take 
zero or one args.  The arg (if there is one) must be of type int.  The 
return type can be either void or int.

If you want to play, you can get the code by
bzr branch http://bzr.wilsonjc.us/foreign/
or by just grabbing the files from that URL manually.  The README 
contains brief instructions on how to try it out.

If I'm just reinventing the wheel, or if you can think of a better way 
to do it, or if you just think I look funny, let me know.
Regards,
Jon Wilson


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Re: Proof of concept dynamic FFI

[Ludovic Courtès]

Hi,

Jon Wilson <jsw@wilsonjc.us> writes:

> I've written a bit of code that lets you call any function from a
> dynamically loaded shared lib with any args.  Well, actually, since it
> is just a proof of concept, it only lets you call functions that take
> zero or one args.  The arg (if there is one) must be of type int.  The
> return type can be either void or int.

Interesting.  If I were to write this, I'd use GNU lightning to compile
natively the glue code instead of having to go through
`foreign-dispatch' (alternatively, there's libffi which can help a bit,
but it adds an indirection).  You also need to make sure that building a
"foreign lambda" is fast since this would typically have to be done a
number of times at startup.

Thanks,
Ludovic.



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Proof of concept dynamic FFI

[Kjetil S. Matheussen]

Jon Wilson:
>
> Hi,
> I've written a bit of code that lets you call any function from a
> dynamically loaded shared lib with any args.  Well, actually, since it
> is just a proof of concept, it only lets you call functions that take
> zero or one args.  The arg (if there is one) must be of type int.  The
> return type can be either void or int.
>
> If you want to play, you can get the code by
> bzr branch http://bzr.wilsonjc.us/foreign/
> or by just grabbing the files from that URL manually.  The README
> contains brief instructions on how to try it out.
>
> If I'm just reinventing the wheel, or if you can think of a better way
> to do it, or if you just think I look funny, let me know.
> Regards,
> Jon Wilson
>


With guile, I usually prefer writing c-code using s-expressions:


(load "eval-c.scm")

(eval-c ""
 	(public
 	 (<void> hello-world (lambda ()
 			       (printf (string "hello world\\n"))))))

(hello-world)
=> hello-world


(eval-c ""
 	(public
 	 (<int> add-ints (lambda ((<int> a)(<int> b))
 			   (return (+ a b))))))
(add-ints 2 3)
=> 5


etc.


http://snd.cvs.sourceforge.net/snd/cvs-snd/eval-c.scm



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