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Contents
module Comparable
# Automatically generate comparitive definitions based on
# attribute fields.
#
# include Comparable[:a, :b]
#
# is equivalent to including a module containing:
#
# def <=>(other)
# cmp = self.a <=> other.a; return cmp unless cmp == 0
# cmp = self.b <=> other.b; return cmp unless cmp == 0
# 0
# end
#
def self.[](*accessors)
Module.new do
include Comparable
define_method(:comparability){ accessors }
define_method(:<=>) do |other|
comparability.each do |a|
cmp = (send(a) <=> other.send(a))
break cmp unless cmp == 0
end
end
end
end
end
# Would it be nice if we could define comparability for all objects?
# Then Comparable[] method would not be needed. Just:
#
# module Comparable
#
# def <=>(other)
# comparability.each do |field|
# cmp = send(field) <=> other.send(field); return cmp unless cmp == 0
# end
# end
#
# end
#
# But I fear it might break other code.
Version data entries
10 entries across 9 versions & 2 rubygems