A simple ActiveRecord extension for declaring raw attributes (not backed by a database column) that should work with composed_of, associations, etc.

raw_attributes.rb

class ActiveRecord::Base
  
  # Defines a shorthand for declaring raw attributes that are not backed by a database column.
  #
  # Equivalent to manually defining getter/setter/query methods that call read/write/query_attribute,
  # but also supports attribute names with characters that are not allowed in normal method names.
  # Unlike +attr_accessor+, these attributes should work with +composed_of+, associations, etc.
  #
  def self.attribute(*names)
    names.each do |name|
      # Define getter, setter and query, supporting characters that are not allowed in normal method names.
      # We prefer +class_eval+ over +define_method+, since the latter creates a closure.
      class_eval <<-STR, __FILE__, __LINE__ + 1
        def __temp__()
          read_attribute(#{name.inspect})
        end
        alias_method '#{name}', :__temp__
        undef_method :__temp__
      STR
      class_eval <<-STR, __FILE__, __LINE__ + 1
        def __temp__=(value)
          write_attribute(#{name.inspect}, value)
        end
        alias_method '#{name}=', :__temp__=
        undef_method :__temp__=
      STR
      class_eval <<-STR, __FILE__, __LINE__ + 1
        def __temp__?(value)
          query_attribute(#{name.inspect})
        end
        alias_method '#{name}?', :__temp__?
        undef_method :__temp__?
      STR
    end
  end
  
end if defined? ActiveRecord::Base