Is this code exception-safe?

 1   class Foo
 2     def initialize
 3       @x = Bar.new
 4       @y = 10
 5       @z = 20
 6     end
 7 
 8     def foo
 9       x = @x
10       @x = @y, @z
11       @y, @z = x
12     end
13   end