I've been reading through perlapi , perlxs , perlxstut and this here book , however I have a problem. I'm trying to create a class, and access one of its attributes from XS code and I get segfault. I tried to do a very simple thing, to write XS that would access an certain position of an arrayref and return it. Maybe I'm using the wrong API ?

this is my class SJT.pm : 

package SJT;

use 5.010000;
use strict;
use warnings;

require Exporter;

our @ISA = qw(Exporter);

our %EXPORT_TAGS = ( 'all' => [ qw(
    
) ] );

our @EXPORT_OK = ( @{ $EXPORT_TAGS{'all'} } );

our @EXPORT = qw(
    
);

our $VERSION = '0.01';

require XSLoader;
XSLoader::load('SJT', $VERSION);


sub new {
    my ($class) = @_;
    return bless {
        permutation => [2,2,2,2,2,2,2,2,2,2,2],
    },$class;
}

[download]
Ok so this is my XS code( SJT.xs): 
package SJT;

use 5.010000;
use strict;
use warnings;

require Exporter;

our @ISA = qw(Exporter);

MODULE = SJT        PACKAGE = SJT        


//THIS FUNCTION SHOULD JUST GET $self->permutation->[index]
int get(self,index)
    SV* self
    int index
    CODE:
        char* key = "permutation";
        AV* array;
        SV* hv = self;
        if(sv_isobject(hv)) {
            printf("self is object,moving on...\n");
        } else {
            printf("SJT::get was expecting self to be an object");
        };

        HV* q = (HV *)SvRV(hv);

        array = *hv_fetch(q,"permutation",11,FALSE);

        if(array==NULL) {
            printf("array not found in self...\n");
            exit(-1);
        }else {
            printf("array found in self %X\n",array);
        };

        SV** res = av_fetch(array,index,FALSE);
        if(res==NULL) {
            printf("item not found in array...\n");
            exit(-1);
        }else {
            printf("also found item in array at: %X\n",res);
        };

[download]
THE FOLLOWING LINE SEGFAULTS 
        
        IV a = SvIV(SvRV(*res));
        printf("right before return\n");
        RETVAL = a;//SvIV(*av_fetch(array,index,FALSE));

    OUTPUT:
        RETVAL

void
set(self,index,value)
    SV* self
    int index;
    int value;
    CODE:
    OUTPUT:

[download]
This is the OUTPUT I get 
ok 1 - use SJT;
SV = RV(0x82807dc) at 0x82807d0
  REFCNT = 1
  FLAGS = (PADMY,ROK)
  RV = 0x82bc750
  SV = PVHV(0x8185174) at 0x82bc750
    REFCNT = 1
    FLAGS = (OBJECT,SHAREKEYS)
    STASH = 0x82bc9e0   "SJT"
    ARRAY = 0x82ccd20  (0:7, 1:1)
    hash quality = 100.0%
    KEYS = 1
    FILL = 1
    MAX = 7
    RITER = -1
    EITER = 0x0
    Elt "permutation" HASH = 0x41573374
    SV = RV(0x82bc6ac) at 0x82bc6a0
      REFCNT = 1
      FLAGS = (ROK)
      RV = 0x8242ce0
      SV = PVAV(0x828d814) at 0x8242ce0
        REFCNT = 1
        FLAGS = ()
        ARRAY = 0x82cbcb8
        FILL = 10
        MAX = 10
        ARYLEN = 0x0
        FLAGS = (REAL)
        Elt No. 0
        SV = IV(0x82bc88c) at 0x82bc890
          REFCNT = 1
          FLAGS = (IOK,pIOK)
          IV = 2
        Elt No. 1
        SV = IV(0x82bc70c) at 0x82bc710
          REFCNT = 1
          FLAGS = (IOK,pIOK)
          IV = 2
        Elt No. 2
        SV = IV(0x82bc6ec) at 0x82bc6f0
          REFCNT = 1
          FLAGS = (IOK,pIOK)
          IV = 2
        Elt No. 3
        SV = IV(0x82bc6fc) at 0x82bc700
          REFCNT = 1
          FLAGS = (IOK,pIOK)
          IV = 2
self is object,moving on...
array found in self 82BC6A0
also found item in array at: 8242CE4
19830 Segmentation fault

[download]
the code I used to get this result was: 

use Devel::Peek;
use Data::Dumper;
use Test::More tests => 1;
BEGIN {
    use_ok('SJT'); 
    my $s1 = SJT->new;
    Dump($s1);
    print "HERE be 2:".$s1->get(1)."\n";
    print "\n";
};

[download]
Why am I getting the segfault, am I using the API wrong ?

In reply to simple XS by spx2

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