use strict;
use warnings;

{
  package Foo;
  my $private = sub {
    my $self = shift;
    print "From $self: @_\n"
  };
  sub public {
    my $self = shift;
    $self->$private( @_ );
  }
}

( bless [], 'Foo' )->public( 'Howdy!' );

__END__
From Foo=ARRAY(0x816cc20): Howdy!