"o|c|out=s" => \my $csv;

##</code><code>##

GetOptions ("length=i" => \$length,    # numeric
            "file=s"   => \$data,      # string
            "verbose"  => \$verbose)   # flag

##</code><code>##

sub GetOptions {
    my %options = @_;
    # ...
}

##</code><code>##

my $sref = \my $scalar;

##</code><code>##

my $scalar;
my $sref = \$scalar;

##</code><code>##

my %hash = (
    some_key => \my $value,
    # ...
);

##</code><code>##

my $value;
my %hash;
$hash{some_key} = \$value;

##</code><code>##

($csv) and ($xls = $csv);

##</code><code>##

$xls = $csv if $csv;

##</code><code>##

sub foo {
    my $value = rand(5);
    return $value > 2 or die "Value was not greater than 2.\n";
}

##</code><code>##

sub foo {
    my $value = rand(5);
    return($value > 2) or die;
}

##</code><code>##

sub foo {
    my $value = rand(5);
    return $value > 2 || die;
}

##</code><code>##

sub foo {
    my $value = rand(5);
    return ( ($value > 2) || die );
}