gistfile1.txt

class Object
    def x
        "Object's x"
    end
end

class MyClass
  x = "hello"
end

def foo
  Object.new.instance_eval {puts x}
end

def bar
  def x; "Boom!"; end
  x = "Hello!"
  Object.new.instance_eval {puts x}
end

foo            #=> Object's x
bar            #=> Hello!
puts MyClass.x #=> Boom!