Contents

require 'traitorous'
module Traitorous
  # Provides a mechanism to test equality of objects that implement a traits hash.
  # This is an iffy concept, and if I didn't happen to be using a Coordinate
  # object in te project this was extracted from it probably wouldn't be a part
  #
  # For this module to work it makes a set of assumptions.
  # 1. The base assumption of the types of objects created using Traitorous is
  #    that they are easily expressed in text.
  # 2. That the aggregate of the traits equality means the 2 are equal
  # 3. If a trait is an Array, each element of the array is tested against the 2nd,
  #    and vice versa.
  # 4. all other equality is tested using ==
  # 5. nested objects should also implement equality to facilitate the
  #    comparisons of deeply nested structures
  #
  # Further expansions might call for the converter to assume an equality guise
  module Equality

    # Override the normal :== method to compare each trait individually when
    # testing equality.
    #
    # Coordinate.new(x: 1, y: 2) == Coordinate.new(x:1, y: 2)

    # @param other_val [#traits] target of comparison
    # @return Boolean if all traits values match return true.
    def ==(other_val)
      return false unless self.class == other_val.class
      traits.keys.all? do |trait_name|
        orig_trait  =      self.send(trait_name.intern)
        other_trait = other_val.send(trait_name.intern)
        array_equality(orig_trait, other_trait) || (orig_trait == other_trait)
      end
    end

    # compare the equality of 2 arrays, and I'm not sure this is the best way to
    # do the comparisons.
    # @params alpha [Array] first array
    # @params beta [Array] second array
    # @return [Boolean] true if every element in 1 array is equal(==) to an
    #   element in the 2nd and vice versa (order doesn't matter, should it?)
    def array_equality(alpha, beta)
      return false unless (alpha.is_a?(Array) && beta.is_a?(Array))
      alpha.all?{|a| beta.any?{|b| a == b}}
    end
  end
end

Version data entries

2 entries across 2 versions & 1 rubygems

Version	Path
traitorous-0.2.2	lib/traitorous/equality.rb
traitorous-0.2.0	lib/traitorous/equality.rb