Re: [Chicken-users] Objective-C interface (sort of...)

[Zbigniew]

Oh, to clarify---unsigned char is always a character.  So uchar return
/ arg types do not accept or convert to predicate values, i.e. an
unsigned char always returns C_make_character(*(unsigned char *)obj);

On 11/26/05, Zbigniew <address@hidden> wrote:
> Yes, they use the natural representation, so if you know from the
> methodReturnType call that a return type is _C_DBL, you can cast the
> return value directly to a double.  E.g. C_flonum(&a, *(double
> *)rbuf);   And _C_CLASS is a Class (struct objc_class *) and _C_ID is
> an id (struct objc_object *).   And so on.
>
> As an aside, and this is probably not news to you, the BOOL type is
> just an alias for signed char.  However, signed char is exceedingly
> rare as a return or argument type, it is almost 100% BOOL.  I found it
> beneficial to implicitly convert a return of (char)0 into #f --- other
> values still return the character itself --- and to convert an signed
> char argument of #f or #t into (char)0 or (char)1 --- though character
> values are still accepted.  This makes Scheme predicates behave
> nicely.  And the rare real signed char returns and args still work,
> with the caveat that a #f return would mean #\x0.
>
> On 11/26/05, felix winkelmann <address@hidden> wrote:
> >
> > Yes, this looks fine. Can one assume the buffer for arguments/return values
> > uses a "natural" representation?
>
> On 11/25/05, Thomas Chust <address@hidden> wrote:
> > >      [inv setArgument:convertArgumentFromScheme(i-2, [sig
> > > getArgumentTypeAtIndex:i])
> > >               atIndex:i];
> > >    [inv invoke];
> > >    void *rbuf = alloca([sig methodReturnLength]);
> > >    [inv getReturnValue:rbuf];
> > >    convertReturnValueToScheme([sig methodReturnType], rbuf);
>