问题 I'm writing a rack middleware component for a rails app that will need to conditionally set cookies. I am currently trying to figure out to set cookies. From googling around it seems like this should work: class RackApp def initialize(app) @app = app end def call(env) @status, @headers, @response = @app.call(env) @response.set_cookie("foo", {:value => "bar", :path => "/", :expires => Time.now+24*60*60}) [@status, @headers, @response] end end which doesn't give errors, but doesn't set a cookie