module Equitable

Equitable

This mixin provides methods of equality based on a single identity method which must return a list of accessors used as the identity keys.

It also provides a “shortcut” for creating the identity method based on given accessors and returns the Equitable module for inclusion.

include Equitable(:a, :b)

is equivalent to including a module containing:

def ==(other)
  self.a == other.a && self.b == other.b
end

def eql?(other)
  self.a.eql?(other.a) && self.b.eql?(other.b)
end

def hash()
  self.a.hash ^ self.b.hash
end

Public Class Methods

identify(base, *accessors) click to toggle source
# File lib/more/facets/equitable.rb, line 73
def self.identify(base, *accessors)
  base.send(:define_method, :identity){ accessors }
  self
end

Public Instance Methods

==(o) click to toggle source
# File lib/more/facets/equitable.rb, line 78
def ==(o)
  identity.all?{ |a| send(a) == o.send(a) }
end
eql?(o) click to toggle source
# File lib/more/facets/equitable.rb, line 82
def eql?(o)
  identity.all?{ |a| send(a).eql?(o.send(a)) }
end
hash() click to toggle source
# File lib/more/facets/equitable.rb, line 86
def hash
  identity.inject(0){ |memo, a| memo ^ send(a).hash }
end