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

my %foo = (
    a => 'b',
    b => 'c',
);

print hash_or_hashref(%foo);
print hash_or_hashref(\%foo);

sub hash_or_hashref {
    die "missing options" unless $_[0];

    # was it a hash or hashref passed.
    my $options;
    if (UNIVERSAL::isa($_[0], 'HASH')) {
        $options = shift;
    } else {
        $options = {@_};
    }

    return $options->{a};
}