From e47b366d6a96502303acecebd5e6d402b764b416 Mon Sep 17 00:00:00 2001
From: Thorsten Eckel <te@znuny.com>
Date: Fri, 1 Sep 2017 14:28:06 +0200
Subject: [PATCH] Refactoring: Replaced custom implementation with Ruby core
 Delegator classes.

---
 lib/mixin/instance_wrapper.rb     | 43 --------------------
 lib/sequencer/units.rb            | 14 +++----
 lib/sequencer/units/attribute.rb  |  2 +-
 lib/sequencer/units/attributes.rb | 66 ++++++++++++++-----------------
 4 files changed, 36 insertions(+), 89 deletions(-)
 delete mode 100644 lib/mixin/instance_wrapper.rb

diff --git a/lib/mixin/instance_wrapper.rb b/lib/mixin/instance_wrapper.rb
deleted file mode 100644
index a7d8d2903..000000000
--- a/lib/mixin/instance_wrapper.rb
+++ /dev/null
@@ -1,43 +0,0 @@
-module Mixin
-  # This modules enables to redirect all calls to methods that are
-  # not defined to the declared instance variable. This comes handy
-  # when you wan't extend a Ruby core class like Hash.
-  # To inherit directly from such classes is a bad idea and should be avoided.
-  # This way allows it indirectly.
-  module InstanceWrapper
-    module ClassMethods
-      # Creates the class macro `wrap` that activates
-      # the wrapping for the given instance variable name.
-      #
-      # @param [Symbol] variable the name of the instance variable to wrap around
-      #
-      # @example
-      #  wrap :@some_hash
-      #
-      # @return [nil]
-      def wrap(variable)
-        define_method(:instance) do
-          instance_variable_get(variable)
-        end
-      end
-    end
-
-    def self.included(base)
-      base.extend(ClassMethods)
-    end
-
-    private
-
-    def method_missing(method, *args, &block)
-      if instance.respond_to?(method)
-        instance.send(method, *args, &block)
-      else
-        super
-      end
-    end
-
-    def respond_to_missing?(method_sym, include_all)
-      instance.respond_to?(method_sym, include_all)
-    end
-  end
-end
diff --git a/lib/sequencer/units.rb b/lib/sequencer/units.rb
index e926ead87..f1adb1bf3 100644
--- a/lib/sequencer/units.rb
+++ b/lib/sequencer/units.rb
@@ -1,11 +1,9 @@
-require 'mixin/instance_wrapper'
+require 'sequencer/units/attribute'
+require 'sequencer/units/attributes'
 
 class Sequencer
-  class Units
+  class Units < SimpleDelegator
     include ::Enumerable
-    include ::Mixin::InstanceWrapper
-
-    wrap :@units
 
     # Initializes a new Sequencer::Units instance with the given Units Array.
     #
@@ -14,7 +12,7 @@ class Sequencer
     # @example
     #  Sequencer::Units.new('Example::Unit', 'Sequencer::Unit::Second::Unit')
     def initialize(*units)
-      @units = units
+      super(units)
     end
 
     # Required #each implementation for ::Enumerable functionality. Constantizes
@@ -27,7 +25,7 @@ class Sequencer
     #
     # @return [nil]
     def each
-      @units.each do |unit|
+      __getobj__.each do |unit|
         yield constantize(unit)
       end
     end
@@ -58,7 +56,7 @@ class Sequencer
     #
     # @return [Object] the Unit class for the requested index
     def [](index)
-      constantize(@units[index])
+      constantize(__getobj__[index])
     end
 
     private
diff --git a/lib/sequencer/units/attribute.rb b/lib/sequencer/units/attribute.rb
index 3e716bb2b..b56dcf544 100644
--- a/lib/sequencer/units/attribute.rb
+++ b/lib/sequencer/units/attribute.rb
@@ -1,5 +1,5 @@
 class Sequencer
-  class Units
+  class Units < SimpleDelegator
     class Attribute
 
       attr_accessor :from, :to
diff --git a/lib/sequencer/units/attributes.rb b/lib/sequencer/units/attributes.rb
index f9d47aa29..9c5a72136 100644
--- a/lib/sequencer/units/attributes.rb
+++ b/lib/sequencer/units/attributes.rb
@@ -1,28 +1,15 @@
-require 'mixin/instance_wrapper'
-
 class Sequencer
-  class Units
-    class Attributes
-      include ::Mixin::InstanceWrapper
+  class Units < SimpleDelegator
 
-      wrap :@attributes
-
-      # Initializes the lifespan store for the attributes
-      # of the given Units declarations.
-      #
-      # @param [Array<Hash{Symbol => Array<:Symbol>}>] declarations the list of Unit declarations.
-      #
-      # @example
-      #  declarations = [{uses: [:attribute1, ...], provides: [:result], ...}]
-      #  attributes = Sequencer::Units::Attributes(declarations)
-      #
-      # @return [nil]
-      def initialize(declarations)
-        @declarations = declarations
-
-        initialize_attributes
-        initialize_lifespan
-      end
+    # Initializes the lifespan store for the attributes
+    # of the given Units declarations.
+    #
+    # @param [Array<Hash{Symbol => Array<:Symbol>}>] declarations the list of Unit declarations.
+    #
+    # @example
+    #  declarations = [{uses: [:attribute1, ...], provides: [:result], ...}]
+    #  attributes = Sequencer::Units::Attributes(declarations)
+    class Attributes < Delegator
 
       # Lists all `provides` declarations of the Units the instance was initialized with.
       #
@@ -61,24 +48,29 @@ class Sequencer
         key?(attribute)
       end
 
-      private
-
-      def initialize_attributes
-        @attributes = Hash.new do |hash, key|
-          hash[key] = Sequencer::Units::Attribute.new
-        end
+      def __getobj__
+        @attributes
       end
 
-      def initialize_lifespan
-        @declarations.each_with_index do |unit, index|
-
-          unit[:uses].try(:each) do |attribute|
-            self[attribute].to = index
+      def __setobj__(declarations)
+        @attributes ||= begin
+          attributes = Hash.new do |hash, key|
+            hash[key] = Sequencer::Units::Attribute.new
           end
 
-          unit[:provides].try(:each) do |attribute|
-            next if self[attribute].will_be_provided?
-            self[attribute].from = index
+          attributes.tap do |result|
+
+            declarations.each_with_index do |unit, index|
+
+              unit[:uses].try(:each) do |attribute|
+                result[attribute].to = index
+              end
+
+              unit[:provides].try(:each) do |attribute|
+                next if result[attribute].will_be_provided?
+                result[attribute].from = index
+              end
+            end
           end
         end
       end