def validates_length_of(*attribute_names)
      options = Macros.extract_options(attribute_names)
      validation_rules.add(Rule::Length, attribute_names, options)
    end
def validates_length_of(*attribute_names)
      options = Macros.extract_options(attribute_names)
      validation_rules.add(Rule::Length, attribute_names, options)
    end
Validates that the length of the attribute is equal to, less than,
 greater than or within a certain range (depending upon the options
 you specify).

 @option [Boolean] :allow_nil (true)
   true or false.

 @option [Boolean] :allow_blank (true)
   true or false.

 @option [Boolean] :minimum
   Ensures that the attribute's length is greater than or equal to
   the supplied value.

 @option [Boolean] :min
   Alias for :minimum.

 @option [Boolean] :maximum
   Ensures the attribute's length is less than or equal to the
   supplied value.

 @option [Boolean] :max
   Alias for :maximum.

 @option [Boolean] :equals
   Ensures the attribute's length is equal to the supplied value.

 @option [Boolean] :is
   Alias for :equals.

 @option [Range] :in
   Given a Range, ensures that the attributes length is include?'ed
   in the Range.

 @option [Range] :within
   Alias for :in.

 @example Usage
   require 'virtus'
   require 'aequitas'

   class Page
     include Virtus
     include Aequitas

     attribute :high,       Integer
     attribute :low,        Integer
     attribute :just_right, Integer

     validates_length_of :high, :min => 100000000000
     validates_length_of :low, :equals => 0
     validates_length_of :just_right, :within => 1..10

     # a call to valid? will return false unless:
     # high is greater than or equal to 100000000000
     # low is equal to 0
     # just_right is between 1 and 10 (inclusive of both 1 and 10)
   end