Factor out redundant code in resource collections

lib/nacre/abstract_collection.rb

@@ -0,0 +1,31 @@
+module Nacre
+  class AbstractCollection
+
+    include Enumerable
+
+    attr_accessor :members
+
+    def initialize(resource_hash = {})
+      self.members = []
+      resource_hash.each_pair do |key, value|
+        members << resource_class.new(key, value)
+      end
+    end
+
+    def each(&block)
+      members.each do |member|
+        block.call(member)
+      end
+    end
+
+    def params
+      members.map { |member| { member.key.to_sym => member.params } }
+    end
+
+    private
+
+    def resource_class
+      raise 'Calling class must define .collection_class'
+    end
+  end
+end

lib/nacre/order/assignment_collection.rb

@@ -1,25 +1,12 @@
-module Nacre
-  class Order::AssignmentCollection
-
-    include Enumerable
-
-    attr_accessor :members
+require 'nacre/abstract_collection'
 
-    def initialize(resource_hash = {})
-      self.members = []
-      resource_hash.each_pair do |key, value|
-        members << Nacre::Order::Assignment.new(key, value)
-      end
-    end
+module Nacre
+  class Order::AssignmentCollection < AbstractCollection
 
-    def each(&block)
-      members.each do |member|
-        block.call(member)
-      end
-    end
+    private
 
-    def params
-      members.map { |member| { member.key.to_sym => member.params } }
+    def resource_class
+      Nacre::Order::Assignment
     end
 
   end

lib/nacre/order/row_collection.rb

@@ -1,25 +1,12 @@
-module Nacre
-  class Order::RowCollection
-
-    include Enumerable
-
-    attr_accessor :members
+require 'nacre/abstract_collection'
 
-    def initialize(resource_hash = {})
-      self.members = []
-      resource_hash.each_pair do |key, value|
-        members << Nacre::Order::Row.new(key, value)
-      end
-    end
+module Nacre
+  class Order::RowCollection < AbstractCollection
 
-    def each(&block)
-      members.each do |member|
-        block.call(member)
-      end
-    end
+    private
 
-    def params
-      members.map { |member| { member.key.to_sym => member.params } }
+    def resource_class
+      Nacre::Order::Row
     end
   end
 end