#!/usr/bin/perl
use warnings;
use strict;
use Syntax::Construct '//';

{   package Previous;
    use Tie::Scalar;
    use parent -norequire => 'Tie::StdScalar';

    sub TIESCALAR { bless \ my $o, shift }
    sub STORE {
        my ($self, $value) = @_;
        warn 'I was ',  $$self // 'undefined', "\n";
        $$self = $value;
    }
}

tie my $p, 'Previous';
$p = $_ for 'a' .. 'z';