On 2004-05-20, at 12:40:10 +0100, Dirk Koopman wrote:
> I am confused.
>
> I have a simple scalar tie which uses an XS routine to do the fetching
> and this all works just fine in perl code.
>
> However, I want to do a "tied" (or magical?) fetch on the same thing in
> XS. When the thing is passed on the stack, it is a reference which
> actually points to an opaque pointer to my internal data dictionary
> system. It seems to me that it is the *reference* that has the magic on
> it, not the dereferenced opaque pointer.
>
> Do I just do an SvNV(refsv) or do I have to dereference the refsv, then
> do something else to invoke the magic.
>
> Effectively this is the perl equivaleny of what I want to do XS:
>
> my $n = $SAL::BAL;
>
> where $SAL::BAL is a tied variable that causes a numeric value contained
> within the system (called SAL::BAL) to be put into $n (this all works).
>
> In my naive way, it would seem that this would be an XS equivalent:
>
> SV *refsv = get_sv("SAL::BAL", 0);
You may want to insert
SvGETMAGIC(refsv);
here. This will call C<mg_get> (which in turn will fetch a value) if
C<refsv> is magical.
> NV d = SvNV(refsv);
>
> But somehow, I doubt it :-)
Have you tried to do it? ;-)
Marcus
--
Law of Continuity:
Experiments should be reproducible. They should all fail the same way.
