gistfile1.rb

def self.by_id(id)
  cached_supplier = @suppliers.find { |s| s.db_id == id }
  return cached_supplier if cached_supplier
  supplier = from_row(DB[:supplier].filter(:supplier_id => id).first)
  @suppliers << supplier
  supplier
end

def self.all
  return @suppliers unless @suppliers.empty?
  @suppliers = DB[:supplier].all.collect { |s| from_row s }
end