Dynamic associations

Using a domain_object field will automatically create an associations method on the domain class being associated to. For example:

class Client < Lafcadio::DomainObject
  string 'client_name'
end

class Invoice < Lafcadio::DomainObject
  date          'date'
  float         'amount'
  domain_object Client
end

...

client = Client[123]
invoices = client.invoices
invoices.each do |inv|
  puts "invoice #{ inv.pk_id } is for $#{ inv.amount }"
end