package _Init;

use strict;
use warnings;

sub new {

    my ($class, %args) = @_;
    my $self = bless { }, ref($class) || $class;
    $self->_init(%args);
    return $self;
}

1;

package Container;
use _Init;
@Container::ISA = qw(_Init);

use strict;
use warnings;

sub _init {
    my ($self, %args) = @_;
    $self->{_default} = [];
}

sub add {
    my $self   = shift @_;
    my $key    = shift @_;
    my $target = shift @_;

    my $aref = $self->{$key};
    push @$aref, $target;
}

sub addtype {
    my $self   = shift @_;
    my $key    = shift @_;
    $self->{$key} = [];
}

sub list {
    my $self = shift @_;
    my $key  = shift @_;
    my $aref = $self->{$key};

    #return $aref wont work as well
     
    #why is $aref broken?
    my $count = 0;
    foreach(@$aref) {
       print "$_\n";
       $count++;
    }

}
sub remove {
    my $self   = shift;
    my $type   = shift @_;
    my $target = shift @_;

    my $aref  = $self->{$type};

    my $count = 0;
    foreach(@$aref) {
        if ($target eq $_) {
            splice @$aref, $count, 1;
        }
        $count++;
    }
}



1;

package main:

$self = Container->new();
$self->addtype("_population");
$self->add("_population", $someobjref);
$self->list("_population");