random_unavailable.rb

class RandomUnavailable < StandardError
  attr_reader :unavailable_method

  def self.for(*methods)
    Module.new do
      singleton_class.send(:define_method, :included) do |klass|
        klass.instance_eval do
          methods.each do |m|
            define_method(m) { raise RandomUnavailable.new(m) }
          end
        end
      end
    end
  end

  def initialize(unavailable_method)
    @unavailable_method = unavailable_method
  end

  def message
    "#{unavailable_method} is not available for use"
  end
end

module Kernel
  include RandomUnavailable.for(:rand, :srand)
  singleton_class.send :include, RandomUnavailable.for(:rand, :srand)
end

class Random
  include RandomUnavailable.for(:rand, :srand)
  singleton_class.send :include, RandomUnavailable.for(:rand, :srand)
end

class Array
  include RandomUnavailable.for(:shuffle, :sample)
end