+The +matches?+ method or the lambda is passed the "+request+ object":http://guides.rubyonrails.org/action_controller_overview.html#the-request-object, which means the constraint can check +request.path_parameters+, +request.headers+ or any other property of the request.
h4. Route Globbing
Route globbing is a way to specify that a particular parameter should be matched to all the remaining parts of a route. For example