move all private methods in to an object

lib/medicine.rb

@@ -1,6 +1,7 @@
 require "medicine/version"
 require "medicine/dependencies"
 require "medicine/injections"
+require "medicine/define_methods"
 require "inflecto"
 
 module Medicine
@@ -24,41 +25,12 @@ def self.prepended(base)
     # @example
     #   new(user_repo: User, role_repo: Role)
     def initialize(*args)
-      @injections = Injections.new(last_hash(args))
-      assert_all_dependencies_met
-      define_dependency_methods
+      DefineMethods.on(self, args)
       super
     end
 
     private
 
-    def last_hash(args)
-      args.last.respond_to?(:[]) ? args.pop : {}
-    end
-
-    def assert_all_dependencies_met
-      raise RequiredDependencyError, "pass all required dependencies (#{unmet_dependencies.join(', ')}) in to initialize" unless unmet_dependencies.empty?
-    end
-
-    def define_dependency_methods
-      dependencies.each do |dependency|
-        define_singleton_method dependency.method_name do
-          @injections.fetch(dependency.name) { dependency.default }
-        end
-        self.singleton_class.class_eval { private dependency.method_name }
-      end
-    end
-
-    def unmet_dependencies
-      dependencies.without_default.select do |dependency|
-        !@injections.include?(dependency.name)
-      end
-    end
-
-    def dependencies
-      self.class.dependencies
-    end
-
     module ClassMethods
       def dependencies
         @dependencies ||= Dependencies.new

lib/medicine/define_methods.rb

@@ -0,0 +1,42 @@
+module Medicine
+  class DefineMethods
+    def self.on(object, injections)
+      new(object, injections).call
+    end
+
+    def initialize(object, args)
+      @object       = object
+      @dependencies = object.class.dependencies
+      @injections   = Injections.new(last_hash(args))
+    end
+
+    def call
+      assert_all_dependencies_met
+      object.instance_variable_set("@injections", injections)
+      dependencies.each do |dependency|
+        object.define_singleton_method dependency.method_name do
+          @injections.fetch(dependency.name) { dependency.default }
+        end
+        object.singleton_class.class_eval { private dependency.method_name }
+      end
+    end
+
+    private
+
+    attr_reader :object, :dependencies, :injections
+
+    def assert_all_dependencies_met
+      raise RequiredDependencyError, "pass all required dependencies (#{unmet_dependencies.join(', ')}) in to initialize" unless unmet_dependencies.empty?
+    end
+
+    def unmet_dependencies
+      dependencies.without_default.select do |dependency|
+        !injections.include?(dependency.name)
+      end
+    end
+
+    def last_hash(args)
+      args.last.respond_to?(:[]) ? args.pop : {}
+    end
+  end
+end