Its called magic :) There is a reason modules on cpan for this, see alias , namespace, and stash

use Data::Dump;
$FOO::ONE = 1;
*BAR:: = *FOO::;
$BAR::ONE = 2;
dd \%BAR::, \%FOO::;
dd \*BAR::;
__END__
do {
  my $a = { ONE => *FOO::ONE };
  $a->{ONE} = \1;
  ($a, $a);
}
do {
  my $a = \*main::FOO::;
  *{$a} = { ONE => *FOO::ONE };
  *{$a}{HASH}{ONE} = \1;
  $a;
}
[download]

use Data::Dump::Streamer;
$FOO::ONE = 1;
*BAR:: = *FOO::;
$BAR::ONE = 2;
Dump \%BAR::, \%FOO::;
Dump \*BAR::;
__END__
$HASH1 = { ONE => *FOO::ONE };
*FOO::ONE = \do { my $v = 1 };
$HASH2 = $HASH1;
$GLOB1 = \*{'::FOO::'};
*{'::FOO::'} = { ONE => *FOO::ONE };
*FOO::ONE = \do { my $v = 1 };
[download]