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Contents
#--
# NOTE Better off as a parameterized module?
#++
class Module
# Generates identity/key methods based on specified attributes.
#
# equate_on :a, :b
#
# _is equivalent to_
#
# def ==(o)
# self.a == o.a && self.b == o.b
# end
#
# def eql?(o)
# self.a.eql?(o.a) && self.b.eql?(o.b)
# end
#
# def hash()
# self.a.hash ^ self.b.hash
# end
#
def equate_on(*fields)
code = ""
code << "def ==(o) " << fields.map {|f| "self.#{f} == o.#{f}" }.join(" && ") << " end\n"
code << "def eql?(o) " << fields.map {|f| "self.#{f}.eql?(o.#{f})" }.join(" && ") << " end\n"
code << "def hash() " << fields.map {|f| "self.#{f}.hash" }.join(" ^ ") << " end\n"
class_eval( code )
fields
end
# Deprecated usage.
alias_method :key_attributes, :equate_on
end
# _____ _
# |_ _|__ ___| |_
# | |/ _ \/ __| __|
# | | __/\__ \ |_
# |_|\___||___/\__|
#
=begin test
require 'test/unit'
class TCModule < Test::Unit::TestCase
def test_equate_on
c = Class.new
c.class_eval { attr_accessor :a, :b ; equate_on :a,:b }
c1,c2 = c.new,c.new
c1.a = 10; c1.b = 20
c2.a = 10; c2.b = 20
assert_equal( c1, c2 )
c1.a = 10; c1.b = 10
c2.a = 10; c2.b = 20
assert_not_equal( c1, c2 )
c1.a = 10; c1.b = 20
c2.a = 20; c2.b = 20
assert_not_equal( c1, c2 )
end
end
=end
Version data entries
26 entries across 26 versions & 1 rubygems