1 files changed, 39 insertions, 0 deletions
diff --git a/railties/lib/rails/deprecation.rb b/railties/lib/rails/deprecation.rb
new file mode 100644
index 0000000000..71adcd61f4
--- /dev/null
+++ b/railties/lib/rails/deprecation.rb
@@ -0,0 +1,39 @@
+require "active_support/string_inquirer"
+require "active_support/basic_object"
+
+module Rails
+  module Initializer
+    def self.run(&block)
+      klass = Class.new(Rails::Application)
+      klass.instance_exec(klass.config, &block)
+      klass.initialize!
+    end
+  end
+
+  class DeprecatedConstant < ActiveSupport::BasicObject
+    def self.deprecate(old, new)
+      constant = self.new(old, new)
+      eval "::#{old} = constant"
+    end
+
+    def initialize(old, new)
+      @old, @new = old, new
+      @target = ::Kernel.eval "proc { #{@new} }"
+      @warned = false
+    end
+
+    def method_missing(meth, *args, &block)
+      ::ActiveSupport::Deprecation.warn("#{@old} is deprecated. Please use #{@new}") unless @warned
+      @warned = true
+
+      target = @target.call
+      if target.respond_to?(meth)
+        target.send(meth, *args, &block)
+      else
+        super
+      end
+    end
+  end
+
+  DeprecatedConstant.deprecate("RAILS_CACHE", "::Rails.cache")
+end