A reader method that returns the value of an instance variable and then resets it to nil

Question

Is there a shorter (and cleaner) way to write the following reader method:

class Foo
  attr_writer :bar

  def bar
    return_value = @bar
    self.bar = nil
    return_value
  end
end

Here's some output on the console to show what it does:

>> foo = Foo.new
=> #<Foo:0x1010e9cf8>
>> foo.bar
=> nil
>> foo.bar = "ok"
=> "ok"
>> foo.bar
=> "ok"
>> foo.bar
=> nil

Answer 1

Don't think so. Looks quite short and clean already to me!

Answer 2

 def bar
   @bar, rv = nil, @bar
   rv
 end

or

 def bar
   (@bar, rv = nil, @bar)[1]
 end

Answer 3

Less clever, but perhaps more clear:

class Foo

  def initialize
    @bar = []
  end

  def bar
    @bar.pop
  end

  def bar= (obj)
    @bar[0] = obj
  end

end

Answer 4

  def bar
    @bar
  ensure
    @bar = nil
  end

This can be a one-liner, if you want:

  def bar
    @bar ensure @bar = nil
  end