#! perl -slw
use strict;
{
    package NewStdScalar;
    require Tie::Scalar;

    our @ISA = qw(Tie::StdScalar);

    sub FETCH { return ${+shift}++ }
}
package main;

tie my $scalar, 'NewStdScalar';

$scalar=0;

print $scalar;             # 0

{
  tie my $scalar, 'NewStdScalar';
  $scalar = "---";     # ---
  print $scalar;
}

print $scalar;             # 1

__END__
C:\test>junk34
0
---
1
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