Here it is slightly clearer description of the problem, you cannot find out what the type is -- attributes calls the appropriate MODIFY handler and that is it, but you can't do FETCH-ing outside of the class, attributes::get will call the wrong FETCH based on caller

#!/usr/bin/perl --
use strict; use warnings;
use attributes();
use Data::Dump;
BEGIN {
    package Junk;
    $INC{'Junk.pm'}=__FILE__;
    use Scalar::Util();
    sub Junk::MODIFY_SCALAR_ATTRIBUTES {
        print "Junk::MODIFY_SCALAR_ATTRIBUTES! @_\n";
        my($package, $scalarref, @attrs) = @_;
        $Junk::attrs{ Scalar::Util::refaddr $scalarref } = \@attrs;
        return;
    }
    sub Junk::FETCH_SCALAR_ATTRIBUTES {
        print "Junk::FETCH_SCALAR_ATTRIBUTES! @_\n";
        my($package, $scalarref) = @_;
        my $attrs = $Junk::attrs{ Scalar::Util::refaddr $scalarref };
        return $attrs ? @$attrs : ();
    }
}


BEGIN {
    package Foo;
    use Scalar::Util();
    sub MODIFY_SCALAR_ATTRIBUTES {
        print "Foo::MODIFY_SCALAR_ATTRIBUTES! @_\n";
        my($package, $scalarref, @attrs) = @_;
        $Foo::attrs{ Scalar::Util::refaddr $scalarref } = \@attrs;
        return;
    }
    sub FETCH_SCALAR_ATTRIBUTES {
        print "Foo::FETCH_SCALAR_ATTRIBUTES! @_\n";
        my($package, $scalarref) = @_;
        my $attrs = $Foo::attrs{ Scalar::Util::refaddr $scalarref };
        return $attrs ? @$attrs : ();
    }
    sub MODIFY_REF_ATTRIBUTES {
        print "Foo::MODIFY_REF_ATTRIBUTES! @_\n";
        my($package, $scalarref, @attrs) = @_;
        $Foo::attrs{ attributes::refaddr $scalarref } = \@attrs;
        return;
    }
    sub FETCH_REF_ATTRIBUTES {
        print "Foo::FETCH_REF_ATTRIBUTES! @_\n";
        my($package, $scalarref) = @_;
        my $attrs = $Foo::attrs{ Scalar::Util::refaddr $scalarref };
        return $attrs ? @$attrs : ();
    }
    sub new {
        print "Foo::new! @_\n";
        my $class = shift;
        return bless { yo => [@_] }, $class ;
    }
}


sub FETCH_SCALAR_ATTRIBUTES {
    print "\nCalling me is a mistake? bug?\n@_\n@{[caller]}\nSince the
+re is no object, you don't know type(package)\n\n";
    return;
}
BEGIN { * FETCH_REF_ATTRIBUTES = \&FETCH_SCALAR_ATTRIBUTES ; }

my Junk $bar :STOOL :CHAIR = 42;
my Foo $new :AND :CHEWY = Foo->new( 42 );


for my $ref( \$bar, \$new ){
    dd  [ $ref, attributes::reftype( $ref ) , attributes::_guess_stash
+( $ref ) ],
        [ attributes::get($ref) ],
        [ attributes::_fetch_attrs($ref) ];;;
    print "\n\n";
}
dd \%Junk::attrs ,  \%Foo::attrs;
__END__
Junk::MODIFY_SCALAR_ATTRIBUTES! Junk SCALAR(0xa38c14) STOOL CHAIR
Foo::new! Foo 42
Foo::MODIFY_SCALAR_ATTRIBUTES! Foo SCALAR(0xa38ca4) AND CHEWY

Calling me is a mistake? bug?
main SCALAR(0xa38c14)
attributes C:/perl/5.14.1/lib/MSWin32-x86-multi-thread/attributes.pm 9
+2
Since there is no object, you don't know type(package)

([\42, "SCALAR", undef], [], [])



Calling me is a mistake? bug?
main REF(0xa38ca4)
attributes C:/perl/5.14.1/lib/MSWin32-x86-multi-thread/attributes.pm 9
+2
Since there is no object, you don't know type(package)

([\bless({ yo => [42] }, "Foo"), "REF", undef], [], [])


(
  { 10718228 => ["STOOL", "CHAIR"] },
  { 10718372 => ["AND", "CHEWY"] },
)
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