Sergey Skvortsov <[EMAIL PROTECTED]> writes:
>Hi.
>
>I can't fully understand why there is need to mark values returned from
>XS-method as "mortal" if they are referenced (owned) by object itself.
There is no such need.
Marking things as mortal just arranges for an SvREFCNT_dec()
on the FREETMPS that is paired with SAVETMPS inside a ENTER/LEAVE
pair.
>void
>get_xs3(self)
> SV *self;
> PREINIT:
> SV **pSV;
> PPCODE:
> pSV = av_fetch((AV*)SvRV(self), 0, 0);
>
> ST(0) = *pSV;
> sv_dump( ST(0) );
> XSRETURN(1);
>
>my $arr = Getter->new(222);
>warn "\n==> XS3\n"; my $v3 = $arr->get_xs3; Dump($v3);
>
>==> XS3
>SV = IV(0x1ab70b0) at 0x15d5c64
> REFCNT = 1
> FLAGS = (IOK,pIOK)
> IV = 222
>SV = IV(0x1ab70bc) at 0x1aef620
> REFCNT = 1
> FLAGS = (PADBUSY,PADMY,IOK,pIOK)
> IV = 222
>
>So we see that returned value is _always_ double-copied.
>It's marvellous.
Well it has to be copied because $v3 has its OWN sv in the 'pad'.
You can only alias SVs of variables using glob hackery
which means they aren't lexicals
our $v4;
*v4 = \$arr->[0];
>
>Just two questions:
>1. What is _exact_ XS-equivalent of "sub { $_[0]->[0];}" ?
There are several ways to write it but in my style it would
be something like:
void
get_xs4(SV *self)
CODE:
{
if (!SvROK(self) || SvTYPE(SvRV(self)) != SVt_PVAV) {
croak("Not an ARRAY reference:%_",self);
}
else {
SV **pSV = av_fetch((AV*)SvRV(self), 0, 0);
if (pSV) {
ST(0) = *pSV;
sv_dump( ST(0) );
XSRETURN(1);
}
else {
XSRETURN_UNDEF;
}
}
}
>2. Is it safe use get_xs3()?
Not if there are holes in your array.
