instance_eval.rb

instance_eval.rb

require 'facets/functor'

class Object

  # Use #instance_eval with a fluid notation.
  #
  #   class X
  #     attr :a
  #     private :a
  #     def initialize
  #       @a = 1
  #     end
  #   end
  #
  #   x = X.new
  #   p x.instance_eval.a  #=> 1
  #   p x.a                #=> Error
  #
  # A useful example might include adding accessors to a metaclass.
  #
  #   class X
  #     metaclass.instance_eval.attr :x
  #   end
  #
  # Will only support calls with blocks as of Ruby 1.8.7+.
  #
  def instance_eval(*args, &block)
    return super if block or !args.empty?
    @_instance_eval ||= Functor.new do |op, *a, &b|
      instance_eval{ send(op, *a, &b) }
    end
  end

end