ReaderMethodCache = { private # We want to generate the methods via module_eval rather than # define_method, because define_method is slower on dispatch. # Evaluating many similar methods may use more memory as the instruction # sequences are duplicated and cached (in MRI). define_method may # be slower on dispatch, but if you're careful about the closure # created, then define_method will consume much less memory. # # But sometimes the database might return columns with # characters that are not allowed in normal method names (like # 'my_column(omg)'. So to work around this we first define with # the __temp__ identifier, and then use alias method to rename # it to what we want. # # We are also defining a constant to hold the frozen string of # the attribute name. Using a constant means that we do not have # to allocate an object on each call to the attribute method. # Making it frozen means that it doesn't get duped when used to # key the @attributes in read_attribute. def method_body(method_name, const_name) <<-EOMETHOD def #{method_name} name = ::ActiveRecord::AttributeMethods::AttrNames::ATTR_#{const_name} _read_attribute(name) { |n| missing_attribute(n, caller) } end EOMETHOD end }.new
ID = 'id'.freeze
Instance Public methods
read_attribute(attr_name, &block)

Returns the value of the attribute identified by attr_name after it has been typecast (for example, “2004-12-12” in a date column is cast to a date object, like, 12, 12)).

# File activerecord/lib/active_record/attribute_methods/read.rb, line 84
def read_attribute(attr_name, &block)
  name = attr_name.to_s
  name = self.class.primary_key if name == ID
  _read_attribute(name, &block)