basicobject.rb

require 'securerandom'

class BasicObject
  def self.singleton_class_of(obj)
    (class <<obj; self; end)
  end

  def self.basic_object?(obj)
    class_of(obj) == ::BasicObject
  end

  def self.object_responds_to?(obj, method_name, priv=false)
    sclass = singleton_class_of(obj)

    sclass.method_defined?(method_name) && (priv || !sclass.private_method_defined?(method_name))
  end

  def self.inspect_object(obj)
    obj.inspect
  rescue ::NoMethodError
    if ::BasicObject.basic_object? obj
      "#<BasicObject:0x%014x>" % (obj.__id__<<1)
    else
      ::Object.instance_method(:inspect).bind(obj).call
    end
  end

  def self.get_instance_variable_of(obj, name)
    obj.instance_variable_get(name)
  rescue ::NoMethodError
    if ::BasicObject.basic_object? obj
      raise ::NameError, "`#{name}' is not allowed as an instance variable name" unless name =~ /\A@[A-Za-z_]\w*\z/
      ::BasicObject.instance_method(:instance_eval).bind(obj).call(name.to_s) # not adding another if just to check whether instance_eval had been removed
    else
      ::Object.instance_method(:instance_variable_get).bind(obj).call(name)
    end
  end

  def self.set_instance_variable_of(obj, name, value)
    obj.instance_variable_set(name)
  rescue ::NoMethodError
    if ::BasicObject.basic_object? obj
      raise ::NameError, "`#{name}' is not allowed as an instance variable name" unless name =~ /\A@[A-Za-z_]\w*\z/
      uuid = ::SecureRandom.uuid
      ::Thread.current[uuid] = value
      obj.instance_eval("#{name} = ::Thread.current['#{uuid}']")
      ::Thread.current[uuid] = nil # no way to delete? odd
    else
      ::Object.instance_method(:instance_variable_set).bind(obj).call(name, value)
    end
  end

  def self.instance_variables_of(obj)
    ::Object.instance_method(:instance_variables).bind(obj).call(*args, &block)
  rescue TypeError
    raise "Sorry Dave, I can't do that" # no way to implement that in pure ruby :(
  end

  def self.class_of(obj)
    ::Object.instance_method(:class).bind(obj).call
  rescue ::TypeError
    ::BasicObject
  end

  def self.send_to(obj, method_name, *args, &block)
    ::BasicObject.instance_method(:__send__).bind(obj).call(method_name, *args, &block)
  end

  def self.instance_eval_in(obj, *args, &block)
    ::BasicObject.instance_method(:instance_eval).bind(obj).call(*args, &block)
  end

  def self.instance_exec_in(obj, *args, &block)
    ::BasicObject.instance_method(:instance_exec).bind(obj).call(*args, &block)
  end
end

__END__
For 2.0:
  define_method(:instance_variables, ::Kernel.instance_method(:instance_variables))
  define_method(:instance_variable_set, ::Kernel.instance_method(:instance_variable_set))
  InstanceVariablesMethod   = instance_method(:instance_variables)
  InstanceVariableSetMethod = instance_method(:instance_variable_set)
  undef_method :instance_variables
  undef_method :instance_variable_set

  def instance_variables_of(obj)
    obj.instance_variables
  rescue ::NoMethodError
    if ::BasicObject.basic_object? obj
      raise NameError: "`#{name}' is not allowed as an instance variable name" unless name =~ /\A@[A-Za-z_]\w*\z/
      ::BasicObject::InstanceVariablesMethod.bind(obj).call
    else
      ::Object.instance_method(:instance_variable_get).bind(obj).call
    end
  end