Tied variables cannot be returned.

sub mysub {
   tie my $tied, 'MyClass';
   return $tied;       # Calls FETCH and returns
}                      # the fetched value.

my $not_tied = mysub();
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Similarly, tied variables cannot be assigned.

tie my $tied, 'MyClass';
my $not_tied = $tied;  # Calls FETCH and assigns
                       # the fetched value.
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However, there's no special limitation on references to tied variables.

sub mysub {
   tie my $tied, 'MyClass';
   return \$tied;      # Returns a ref to the tied var.

my $ref_to_tied1 = mysub();
my $ref_to_tied2 = $ref_to_tied;

print($$ref_to_tied1, "\n");  # Calls $tied's FETCH.
print($$ref_to_tied2, "\n");  # Calls $tied's FETCH.
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