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Contents
# = uninheritable.rb
#
# == Copyright (c) 2003 Austin Ziegler
#
# Ruby License
#
# This module is free software. You may use, modify, and/or redistribute this
# software under the same terms as Ruby.
#
# This program is distributed in the hope that it will be useful, but WITHOUT
# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
# FOR A PARTICULAR PURPOSE.
#
# == Author(s)
#
# * Austin Ziegler
# Author:: Austin Ziegler
# Copyright:: Copyright (c) 2003 Austin Ziegler
# License:: Ruby License
# = Uninheritable
#
# Allows an object to declare itself as unable to be subclassed. The
# technique behind this is very simple (redefinition of #inherited), so this
# just provides an easier way to do the same thing with a consistent error
# message.
#
# == Usage
#
# class A
# extend Uninheritable
# end
#
# class B < A; end # => raises TypeError
#
module Uninheritable
# Redefines a class's #inherited definition to prevent subclassing of the
# class extended by this module.
def inherited(klass)
raise TypeError, "Class #{self} cannot be subclassed."
end
end
# _____ _
# |_ _|__ ___| |_
# | |/ _ \/ __| __|
# | | __/\__ \ |_
# |_|\___||___/\__|
#
=begin testing
require 'test/unit'
class TC_Uninheritable < Test::Unit::TestCase
class Cannot
extend Uninheritable
end
class Can
end
def test_module
assert_nothing_raised {
self.instance_eval <<-EOS
class A < Can; end
EOS
}
assert_raises(TypeError, "Class Cannot cannot be subclassed.") do
self.instance_eval <<-EOS
class B < Cannot; end
EOS
end
end
end
=end
Version data entries
16 entries across 16 versions & 1 rubygems