1 files changed, 14 insertions, 12 deletions
diff --git a/actionpack/lib/action_controller/metal/conditional_get.rb b/actionpack/lib/action_controller/metal/conditional_get.rb
index 480e265e44..06b6a95ff8 100644
--- a/actionpack/lib/action_controller/metal/conditional_get.rb
+++ b/actionpack/lib/action_controller/metal/conditional_get.rb
@@ -1,4 +1,6 @@
-require 'active_support/core_ext/hash/keys'
+# frozen_string_literal: true
+
+require "active_support/core_ext/hash/keys"
 
 module ActionController
   module ConditionalGet
@@ -7,8 +9,7 @@ module ActionController
     include Head
 
     included do
-      class_attribute :etaggers
-      self.etaggers = []
+      class_attribute :etaggers, default: []
     end
 
     module ClassMethods
@@ -129,7 +130,7 @@ module ActionController
     # * <tt>:etag</tt> Sets a "weak" ETag validator on the response. See the
     #   +:weak_etag+ option.
     # * <tt>:weak_etag</tt> Sets a "weak" ETag validator on the response.
-    #   requests that set If-None-Match header may return a 304 Not Modified
+    #   Requests that set If-None-Match header may return a 304 Not Modified
     #   response if it matches the ETag exactly. A weak ETag indicates semantic
     #   equivalence, not byte-for-byte equality, so they're good for caching
     #   HTML pages in browser caches. They can't be used for responses that
@@ -227,25 +228,26 @@ module ActionController
     #   expires_in 3.hours, public: true, must_revalidate: true
     #
     # This method will overwrite an existing Cache-Control header.
-    # See http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html for more possibilities.
+    # See https://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html for more possibilities.
     #
     # The method will also ensure an HTTP Date header for client compatibility.
     def expires_in(seconds, options = {})
       response.cache_control.merge!(
-        :max_age         => seconds,
-        :public          => options.delete(:public),
-        :must_revalidate => options.delete(:must_revalidate)
+        max_age: seconds,
+        public: options.delete(:public),
+        must_revalidate: options.delete(:must_revalidate)
       )
       options.delete(:private)
 
-      response.cache_control[:extras] = options.map {|k,v| "#{k}=#{v}"}
+      response.cache_control[:extras] = options.map { |k, v| "#{k}=#{v}" }
       response.date = Time.now unless response.date?
     end
 
-    # Sets an HTTP 1.1 Cache-Control header of <tt>no-cache</tt> so no caching should
-    # occur by the browser or intermediate caches (like caching proxy servers).
+    # Sets an HTTP 1.1 Cache-Control header of <tt>no-cache</tt>. This means the
+    # resource will be marked as stale, so clients must always revalidate.
+    # Intermediate/browser caches may still store the asset.
     def expires_now
-      response.cache_control.replace(:no_cache => true)
+      response.cache_control.replace(no_cache: true)
     end
 
     # Cache or yield the block. The cache is supposed to never expire.