use warnings;
use strict;

my @matrix;
tie @matrix, 'my_spreadsheet_matrix', (
    [ '$x',   '$y'   ],
    [ '$x+1', '$y+1' ],
    [ '$x+7', '$y+7' ],
);

my ($x, $y) = (7, 9);
print "$matrix[1][1]\n";

($x, $y) = (13, 27);
print "$matrix[1][1]\n";

exit 0;


package my_spreadsheet_matrix;

use warnings;
use strict;
use Tie::Array;

use base 'Tie::StdArray';

1;

sub FETCH {
    my $this = shift;
    my $that = $this->SUPER::FETCH(@_);

    return $that if ref $that;
    $that = eval $that; die $@ if $@;
    return $that;
}

sub TIEARRAY {
    my $class = shift;
    my $this  = bless [], $class;

    for my $e (@_) {
        if( ref $e ) {
            tie @$e, $class, @$e;
        }
                                                                                            
        push @$this, $e;
    }

    return $this;
}