Refactor fallbacks plugin

CHANGELOG.md

@@ -14,6 +14,8 @@
   ([#424](https://github.com/shioyama/mobility/pull/424))
 - Pass `model_class` to `Mobility::Backend#configure` via class method rather
   than on options hash ([#429](https://github.com/shioyama/mobility/pull/429))
+- Remove `Mobility.new_fallbacks` and `Configuration#fallbacks_generator`
+  ([#433](https://github.com/shioyama/mobility/pull/433))
 
 ## 0.8
 

lib/mobility.rb

@@ -27,7 +27,6 @@ class Error < StandardError
   require "mobility/backend"
   require "mobility/backends"
   require "mobility/configuration"
-  require "mobility/fallbacks"
   require "mobility/plugin"
   require "mobility/plugins"
   require "mobility/attributes"
@@ -113,11 +112,6 @@ def config
       end
     end
 
-    # (see Mobility::Configuration#new_fallbacks)
-    def new_fallbacks(*args)
-      config.public_send(:new_fallbacks, *args)
-    end
-
     # Configure Mobility
     # @yield [Mobility::Configuration] Mobility configuration
     def configure

lib/mobility/configuration.rb

@@ -23,23 +23,6 @@ def plugins(*args, &block)
       attributes_class.plugins(&block)
     end
 
-    # Generate new fallbacks instance
-    # @note This method will call the proc defined in the variable set by the
-    # +fallbacks_generator=+ setter, passing the first argument to its `call`
-    # method. By default the generator returns an instance of
-    # +I18n::Locale::Fallbacks+.
-    # @param fallbacks [Hash] Fallbacks hash passed to generator
-    # @return [I18n::Locale::Fallbacks]
-    def new_fallbacks(fallbacks = {})
-      @fallbacks_generator.call(fallbacks)
-    end
-
-    # Assign proc which, passed a set of fallbacks, returns a default fallbacks
-    # instance. By default this is a proc which takes fallbacks and returns an
-    # instance of +I18n::Locale::Fallbacks+.
-    # @param [Proc] fallbacks generator
-    attr_writer :fallbacks_generator
-
     # Default backend to use (can be symbol or actual backend class)
     # @return [Symbol,Class]
     def default_backend
@@ -48,7 +31,6 @@ def default_backend
 
     def initialize
       @accessor_method = :translates
-      @fallbacks_generator = lambda { |fallbacks| Mobility::Fallbacks.build(fallbacks) }
     end
 
     def attributes_class

lib/mobility/plugins/fallbacks.rb

@@ -131,11 +131,25 @@ module Fallbacks
       # on model if option is +false+.
       included_hook do |_, backend_class|
         fallbacks = options[:fallbacks]
-        backend_class.include(Methods.new(fallbacks)) unless fallbacks == false
+        backend_class.include(BackendReader.new(fallbacks, method(:generate_fallbacks))) unless fallbacks == false
       end
 
-      class Methods < Module
-        def initialize(fallbacks_option)
+      private
+
+      def generate_fallbacks(fallbacks)
+        fallbacks_class = I18n.respond_to?(:fallbacks) ? I18nFallbacks : I18n::Locale::Fallbacks
+        fallbacks_class.new(fallbacks)
+      end
+
+      class I18nFallbacks < ::I18n::Locale::Fallbacks
+        def [](locale)
+          super | I18n.fallbacks[locale]
+        end
+      end
+
+      class BackendReader < Module
+        def initialize(fallbacks_option, fallbacks_generator)
+          @fallbacks_generator = fallbacks_generator
           define_read(convert_option_to_fallbacks(fallbacks_option))
         end
 
@@ -157,9 +171,9 @@ def define_read(fallbacks)
 
         def convert_option_to_fallbacks(option)
           if option.is_a?(::Hash)
-            Mobility.new_fallbacks(option)
+            @fallbacks_generator[option]
           elsif option == true
-            Mobility.new_fallbacks
+            @fallbacks_generator[{}]
           else
             ::Hash.new { [] }
           end

spec/mobility/configuration_spec.rb

@@ -3,10 +3,6 @@
 describe Mobility::Configuration do
   subject { Mobility::Configuration.new }
 
-  it "initializes new fallbacks instance to I18n::Locale::Fallbacks.new" do
-    expect(subject.new_fallbacks).to be_a(I18n::Locale::Fallbacks)
-  end
-
   it "sets default_backend to nil" do
     expect(subject.default_backend).to eq(nil)
   end

spec/mobility/plugins/fallbacks_spec.rb

@@ -121,4 +121,28 @@
       expect(backend.read(:'en-US', fallback: true)).to eq(nil)
     end
   end
+
+  # We've taken away the ability to customize the fallbacks generator from
+  # configuration, but it is still possible by overriding a private method on
+  # the Attributes class.
+  describe "overriding fallbacks generator" do
+    plugin_setup do
+      fallbacks true
+    end
+
+    before do
+      attributes_class.class_eval do
+        private
+
+        def generate_fallbacks(_)
+          Hash.new([])
+        end
+      end
+    end
+
+    it "uses overridden fallbacks generator" do
+      expect(listener).to receive(:read).once.with(:'en-US', any_args).and_return(nil)
+      expect(backend.read(:'en-US', fallback: true)).to eq(nil)
+    end
+  end
 end