The run_require_slash plugin makes
r.run a no-op if the remaining path is not empty and does not start with
/. The Rack SPEC requires that
PATH_INFO start with a slash if not empty, so this plugin prevents dispatching to the application with an environment that would violate the Rack SPEC.
You are unlikely to want to use this plugin unless are consuming partial segments of the request path, or using the match_affix plugin to change how routing is done:
plugin :match_affix, "", /(\/|\z)/ route do |r| r.on "/a" do r.on "b" do r.run App end end end # with run_require_slash: # GET /a/b/e => App not dispatched to # GET /a/b => App gets "" as PATH_INFO # with run_require_slash: # GET /a/b/e => App gets "e" as PATH_INFO, violating rack SPEC # GET /a/b => App gets "" as PATH_INFO