# Multiton module that ensures only one object to be allocated for a given
# argument list.
#
# The 'multiton' pattern is similar to a singleton, but instead of only one
# instance, there are several similar instances.  it's usefull when you want to
# avoid constructing objects many times because of some huge expence (connecting
# to a database for example), require a set of similar but not identical
# objects, and cannot easily control how many time a contructor may be called.
#
# Usage:
# class SomeMultitonClass
#   include Multiton
#   attr :arg
#   def initialize(arg)
#     @arg = arg
#   end
# end
#
# a = SomeMultitonClass.instance(4)
# b = SomeMultitonClass.instance(4)	# a and b are same object
# c = SomeMultitonClass.instance(2)     # c is a different object
#
# print([a.arg,b.arg].max, c.arg, "\n")
#
# a = SomeMultitonClass.new		# error (`new' is private)

to install

  sudo su

  ruby ./install.rb