ref threads->create(...)

##</code><code>##

    $inter->{THR} = threads->create(sub{$thread->(\$inter->{INT1})});

##</code><code>##

package HardThread;

use strict;
use warnings;
use threads;
use threads::shared;
use vars qw( $internal );

## Variable declaration for internal functions
my ( $thread );

sub new {
    my $class = shift;
    my $inter : shared = shared_clone({});
    $inter->{INT1}    = "internal 1";
    $inter->{INT2}    = "internal 2";
    $inter->{INT3}    = "internal 5"; 
    my $self = {};
    $self->{inter} = $inter;
    return bless $self, $class;
}

sub stop_thread {
    my $self = shift;
    $self->{THR}->kill('TERM');
    $self->{THR}->join();
}

sub starter {
    my $self = shift;
    my $inter = $self->{inter};
    $self->{THR} = threads->create(sub{$thread->(\$inter->{INT1})});
    return    ( 1 );
}

sub set_internal {
    my $self = shift;
    my $inter = $self->{inter};
    if( @_ ) {
        my ( $given_key, $given_value ) = @_ if @_;
        $inter->{$given_key} = $given_value;
        return    ( 1 );
    }
    return    ( 0 );
}

sub printer {
    my $self = shift;
    my $inter = $self->{inter};
    foreach my $key ( keys %{$inter} ) {
        print $key, " - ", $inter->{$key}, "\n";
    }
}

$thread = sub {
    local *internal = $_[0];
    my $control = 1;
    $SIG{'TERM'} = sub { $control = 0; };
    while( $control == 1 ) {
        print "Thread shows internal value:   ", $internal, "\n";
        sleep 2;
    }
    return    ( 1 );
};

1;

##</code><code>##

    $self->{inter}   # access to shared data
    $self->{THR}     # access to thread