Stop relying on mutable structures in the FileUpdateChecker

1 files changed, 4 insertions, 15 deletions

diff --git a/activesupport/lib/active_support/file_update_checker.rb b/activesupport/lib/active_support/file_update_checker.rb
index 8860636168..48c39d9370 100644
--- a/activesupport/lib/active_support/file_update_checker.rb
+++ b/activesupport/lib/active_support/file_update_checker.rb
@@ -35,22 +35,11 @@ module ActiveSupport
     # 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