Re: Dereferencing array elements with AllegroCL - how?

On Mon, 25 Aug 2003 21:00:49 -0600, Kevin Rosenberg <kevin-HJRc7zDS/[email protected]> wrote:

> Edi Weitz wrote:
> >   CL-USER(2): (uffi:deref-array (uffi:allocate-foreign-object :int 4) :int 2)
> >   Error: slot name 2 can't be used for type
> >          #S(FOREIGN-FUNCTIONS::SIZED-FTYPE-PRIM :KIND :INT :WIDTH 4
> >                                                 :OFFSET 0 :ALIGN 4)
> >     [condition type: SIMPLE-ERROR]
> > 
> > Is that not the right way to create an array and then dereference one
> > of its elements? It works with CMUCL, LW, SBCL so I thought I was on
> > the right track.
> 
> I think this same issue came up on another you asked about.

Really? Oh my, my memory.... :(

> I haven't tested it for this example, but in general, you must pass
> an array type to deref-array. You can look for examples in
> tests/arrays.lisp.
> 
> So, 
> (uffi:deref-array (uffi:allocate-foreign-object :int 4) 
>     '(:array :int) 2)
> should work

Yes, RTFM... :)

I think I'm bitten by this because it is kind of counter-intuitive, or
rather redunant, to me. The operator is DEREF-ARRAY, so it should be
clear that the type is an array. Wouldn't it suffice to provide the
type of the array's elements?

Anyway, just nitpicking.

Thanks,
Edi.