module TablePrint::Printable

def self.default_display_methods(target)
  if target.class.respond_to? :columns
    if target.class.columns.first.respond_to? :name
      # eg ActiveRecord
      return target.class.columns.collect(&:name)
    else
      # eg Sequel
      return target.class.columns
    end
  end
  # eg mongoid
  return target.fields.keys if target.respond_to? :fields and target.fields.is_a? Hash
  return target.keys if target.is_a? Hash
  return target.members.collect(&:to_sym) if target.is_a? Struct
  methods = []
  target.methods.each do |method_name|
    method = target.method(method_name)
    if method.owner == target.class
      if method.arity == 0 #
        methods << method_name.to_s
      end
    end
  end
  methods.delete_if { |m| m[-1].chr == "!" } # don't use dangerous methods
  methods
end