package Fiets::Cache;
use strict; use warnings;
...
sub new {
    my ($self,$class)=@_;
    my $cdir =  Fiets::getvar('cachedir');
    if ($cdir) {
        use Cache::FileCache;
        use base qw(Cache::FileCache);
        $self=Cache::FileCache->new({
            'cache_root' => $cdir,
            'default_expires_in' => '4 h'
        });
    } else {
        use Cache::NullCache;
        use base qw(Cache::NullCache);
        $self=Cache::NullCache->new({
            'default_expires_in' => '4 h',
        });
    }
    bless ($self,$class);
    return $self;
}
...
1;