This'll work for ya:

#!/usr/bin/perl -w
use strict;

package TieTimeArray;

sub TIEARRAY
{
    my $class = shift;
    my $self;
    $self->{ltime} = [localtime];
    bless($self, $class);
}
sub FETCH     { my ($self, $index) = @_; $self->{ltime}= [localtime]; 
+return $self->{ltime}->[$index] }
sub FETCHSIZE { my $self = shift; return scalar @{$self->{ltime}} }

package main;

my @now; tie (@now, "TieTimeArray");
while (1) { print "@now\n"; sleep 1 }
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The reason yours wasnt working before was because you didn't intitialize localtime in the constructor. However, your FETCH wouldnt work anyways because you were trying to return an array when a scalar was expected. FETCH returns the next element of the array, not the entire thing. Also, I stored your data in the object itself, which is handy just in case you need to reference it later. Finally, I threw in the 2 argument form of bless just in case that the class might need to be subclassed later. Its good practice to do anyways :)