move #helpers (delegates to HelperProxy) to module

Since the #helpers interface lives in a module, we
can now re-use the HelperProxy logic in custom
"Presenter" classes which do not inherit from
Draper::Decorator. These custom classes may either
wrap 1..N different collections of AR models
and/or POROs.

lib/draper.rb

@@ -3,6 +3,7 @@ require 'action_view'
 require 'draper/version'
 require 'draper/system'
 require 'draper/active_model_support'
+require 'draper/view_helpers'
 require 'draper/decorator'
 require 'draper/helper_proxy'
 require 'draper/lazy_helpers'

lib/draper/decorator.rb

@@ -4,6 +4,7 @@ require 'active_support/core_ext/array/extract_options'
 module Draper
   class Decorator
     include ActiveModelSupport
+    include Draper::ViewHelpers
 
     class_attribute :model_class
     attr_accessor :model, :options
@@ -162,34 +163,6 @@ module Draper
       decorate(model_class.last, options)
     end
 
-    # Access the helpers proxy to call built-in and user-defined
-    # Rails helpers. Aliased to `h` for convenience.
-    #
-    # @return [HelperProxy] the helpers proxy
-    def helpers
-      self.class.helpers
-    end
-    alias :h :helpers
-
-    # Localize is something that's used quite often. Even though
-    # it's available through helpers, that's annoying. Aliased
-    # to `l` for convenience.
-    def localize(*args)
-      helpers.localize(*args)
-    end
-    alias :l :localize
-
-    # Access the helpers proxy to call built-in and user-defined
-    # Rails helpers from a class context.
-    #
-    # @return [HelperProxy] the helpers proxy
-    class << self
-      def helpers
-        @helpers ||= HelperProxy.new
-      end
-      alias :h :helpers
-    end
-
     # Fetch the original wrapped model.
     #
     # @return [Object] original_model

lib/draper/view_helpers.rb

@@ -0,0 +1,36 @@
+module Draper
+  module ViewHelpers
+    extend ActiveSupport::Concern
+
+    module ClassMethods
+
+      # Access the helpers proxy to call built-in and user-defined
+      # Rails helpers from a class context.
+      #
+      # @return [HelperProxy] the helpers proxy
+      def helpers
+        @helpers ||= Draper::HelperProxy.new
+      end
+      alias :h :helpers
+
+    end
+
+    # Access the helpers proxy to call built-in and user-defined
+    # Rails helpers. Aliased to `h` for convenience.
+    #
+    # @return [HelperProxy] the helpers proxy
+    def helpers
+      self.class.helpers
+    end
+    alias :h :helpers
+
+    # Localize is something that's used quite often. Even though
+    # it's available through helpers, that's annoying. Aliased
+    # to `l` for convenience.
+    def localize(*args)
+      helpers.localize(*args)
+    end
+    alias :l :localize
+
+  end
+end

spec/draper/view_helpers_spec.rb

@@ -0,0 +1,41 @@
+require 'spec_helper'
+
+describe Draper::ViewHelpers do
+  let(:helper_proxy) { Draper::HelperProxy.new }
+  let(:view_context) { Object.new }
+  before { view_helpers.helpers.stub(:view_context).and_return(view_context) }
+
+  subject { Class.new { include Draper::ViewHelpers } }
+  let(:view_helpers) { subject.new }
+
+  describe "#helpers" do
+    it "returns a HelperProxy" do
+      view_helpers.helpers.should be_a Draper::HelperProxy
+    end
+
+    it "is aliased to #h" do
+      view_helpers.h.should be subject.helpers
+    end
+  end
+
+  it "delegates #localize to #helpers" do
+    view_context.should_receive(:localize).with(Date.new)
+    view_helpers.localize(Date.new)
+  end
+
+  it "aliases #l to #localize" do
+    view_context.should_receive(:localize).with(Date.new)
+    view_helpers.l(Date.new)
+  end
+
+  describe ".helpers" do
+    it "returns a HelperProxy" do
+      subject.helpers.should be_a Draper::HelperProxy
+    end
+
+    it "is aliased to #h" do
+      subject.h.should be subject.helpers
+    end
+  end
+
+end