Looking at the FETCH subroutine of Tie::IxHash solves the problem: 
sub FETCH {
  my($s, $k) = (shift, shift);
  return exists( $s->[0]{$k} ) ? $s->[2][ $s->[0]{$k} ] : undef;  
}

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You haven't stored anything in the hash yet, so $_[0]->{val}->{one} returns undef, which isn't an lvalue.

Suggested and untested solution: $h {one} = undef after the tie.

Abigail

In reply to Re: lvalue trickery by Abigail-II
in thread lvalue trickery by broquaint

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