1 files changed, 77 insertions, 0 deletions
diff --git a/activesupport/lib/active_support/dependencies/autoload.rb b/activesupport/lib/active_support/dependencies/autoload.rb
new file mode 100644
index 0000000000..c0dba5f7fd
--- /dev/null
+++ b/activesupport/lib/active_support/dependencies/autoload.rb
@@ -0,0 +1,77 @@
+require "active_support/inflector/methods"
+
+module ActiveSupport
+  # Autoload and eager load conveniences for your library.
+  #
+  # This module allows you to define autoloads based on
+  # Rails conventions (i.e. no need to define the path
+  # it is automatically guessed based on the filename)
+  # and also define a set of constants that needs to be
+  # eager loaded:
+  #
+  #   module MyLib
+  #     extend ActiveSupport::Autoload
+  #
+  #     autoload :Model
+  #
+  #     eager_autoload do
+  #       autoload :Cache
+  #     end
+  #   end
+  #
+  # Then your library can be eager loaded by simply calling:
+  #
+  #   MyLib.eager_load!
+  module Autoload
+    def self.extended(base) # :nodoc:
+      base.class_eval do
+        @_autoloads = {}
+        @_under_path = nil
+        @_at_path = nil
+        @_eager_autoload = false
+      end
+    end
+
+    def autoload(const_name, path = @_at_path)
+      unless path
+        full = [name, @_under_path, const_name.to_s].compact.join("::")
+        path = Inflector.underscore(full)
+      end
+
+      if @_eager_autoload
+        @_autoloads[const_name] = path
+      end
+
+      super const_name, path
+    end
+
+    def autoload_under(path)
+      @_under_path, old_path = path, @_under_path
+      yield
+    ensure
+      @_under_path = old_path
+    end
+
+    def autoload_at(path)
+      @_at_path, old_path = path, @_at_path
+      yield
+    ensure
+      @_at_path = old_path
+    end
+
+    def eager_autoload
+      old_eager, @_eager_autoload = @_eager_autoload, true
+      yield
+    ensure
+      @_eager_autoload = old_eager
+    end
+
+    def eager_load!
+      @_autoloads.values.each { |file| require file }
+    end
+
+    def autoloads
+      @_autoloads
+    end
+  end
+end