%myhash = (
    set0 => [ "a", "b" ],
    set1 => [ "c", "d" ],
);

##</code><code>##

sub updatevars {
    my $set = shift;
    $var1 = $myhash{$set}[0];
    $var2 = $myhash{$set}[1];
}

##</code><code>##

my ($var1,$var2);

updatevars("set0");