Stop relying on mutable structures in the FileUpdateChecker

Author: josevalim

activesupport/lib/active_support/file_update_checker.rb

@@ -35,22 +35,11 @@ class FileUpdateChecker
     # have directories as keys and the value is an array of extensions to be
     # watched under that directory.
     #
-    # This method must also receive a block that will be called once a path changes.
-    #
-    # == Implementation details
-    #
-    # This particular implementation checks for added, updated, and removed
-    # files. Directories lookup are compiled to a glob for performance.
-    # Therefore, while someone can add new files to the +files+ array after
-    # initialization (and parts of Rails do depend on this feature), adding
-    # new directories after initialization is not supported.
-    #
-    # Notice that other objects that implement the FileUpdateChecker API may
-    # not even allow new files to be added after initialization. If this
-    # is the case, we recommend freezing the +files+ after initialization to
-    # avoid changes that won't make effect.
+    # This method must also receive a block that will be called once a path
+    # changes. The array of files and list of directories cannot be changed
+    # after FileUpdateChecker has been initialized.
     def initialize(files, dirs={}, &block)
-      @files = files
+      @files = files.freeze
       @glob  = compile_glob(dirs)
       @block = block
 

activesupport/lib/active_support/i18n_railtie.rb

@@ -9,25 +9,6 @@ class Railtie < Rails::Railtie
     config.i18n.load_path = []
     config.i18n.fallbacks = ActiveSupport::OrderedOptions.new
 
-    def self.reloader
-      @reloader ||= ActiveSupport::FileUpdateChecker.new(reloader_paths){ I18n.reload! }
-    end
-
-    def self.reloader_paths
-      @reloader_paths ||= []
-    end
-
-    # Add <tt>I18n::Railtie.reloader</tt> to ActionDispatch callbacks. Since, at this
-    # point, no path was added to the reloader, I18n.reload! is not triggered
-    # on to_prepare callbacks. This will only happen on the config.after_initialize
-    # callback below.
-    initializer "i18n.callbacks" do |app|
-      app.reloaders << I18n::Railtie.reloader
-      ActionDispatch::Reloader.to_prepare do
-        I18n::Railtie.reloader.execute_if_updated
-      end
-    end
-
     # Set the i18n configuration after initialization since a lot of
     # configuration is still usually done in application initializers.
     config.after_initialize do |app|
@@ -63,7 +44,9 @@ def self.initialize_i18n(app)
 
       init_fallbacks(fallbacks) if fallbacks && validate_fallbacks(fallbacks)
 
-      reloader_paths.concat I18n.load_path
+      reloader = ActiveSupport::FileUpdateChecker.new(I18n.load_path.dup){ I18n.reload! }
+      app.reloaders << reloader
+      ActionDispatch::Reloader.to_prepare { reloader.execute_if_updated }
       reloader.execute
 
       @i18n_inited = true