Paranoid Hash.rb

# Alex MacCaw
# info@eribium.org

# Paranoid Hash
# This is so you don't need to validate options on initialize - as you may not require all the options for every method. 
# You can validate them as the program runs - so you don't get unexpected nils.
# I still haven't decided whether this is a good idea or not ;)

# class Foo
#   attr_reader :options
#   def initialize(options = {})
#     @options = options
#   end
#   
#   def options!
#     @paranoid_ops ||= options.dup.to_paranoid
#   end
#   
#   def bar
#     options![:bar]
#   end
# end
# 
# foo = Foo.new({:one => 1});
# foo.bar # raises error
# 
# foo = Foo.new({:bar => 1});
# foo.bar #=> 1

class Hash
  class ParanoidHashError < StandardError; end
  def to_paranoid
    instance_eval do
      def [](key)
        value = super(key)
        return value unless value == nil 
        raise ParanoidHashError.new("You must specify '#{key}' as an option")
      end
    end
    self
  end
end