Introduced new simple provider structure to DRY up Units and enforce sanitized naming.

lib/sequencer/unit/common/fallback_provider.rb

@@ -1,29 +0,0 @@
-class Sequencer
-  class Unit
-    module Common
-      class FallbackProvider < Sequencer::Unit::Base
-
-        def process
-          provides = self.class.provides
-          raise 'Only one provide attribute possible' if provides.size != 1
-
-          attribute = provides.first
-          return if state.provided?(attribute)
-
-          result = fallback
-
-          # don't store nil values which are default anyway
-          return if result.nil?
-
-          state.provide(attribute, result)
-        end
-
-        private
-
-        def fallback
-          raise 'Missing implementation of fallback method'
-        end
-      end
-    end
-  end
-end

lib/sequencer/unit/common/provider/attribute.rb

@@ -0,0 +1,36 @@
+class Sequencer
+  class Unit
+    module Common
+      module Provider
+        class Attribute < Sequencer::Unit::Base
+
+          def process
+            return if ignore?
+            state.provide(attribute, value)
+          end
+
+          private
+
+          def attribute
+            @attribute ||= provides
+          end
+
+          def provides
+            provides_list = self.class.provides
+            raise "Only single provide attribute possible for class #{self.class.name}" if provides_list.size != 1
+            provides_list.first
+          end
+
+          def value
+            @value ||= send(attribute)
+          end
+
+          def ignore?
+            # don't store nil values which are default anyway
+            value.nil?
+          end
+        end
+      end
+    end
+  end
+end

lib/sequencer/unit/common/provider/fallback.rb

@@ -0,0 +1,16 @@
+class Sequencer
+  class Unit
+    module Common
+      module Provider
+        class Fallback < Sequencer::Unit::Common::Provider::Attribute
+
+          private
+
+          def ignore?
+            state.provided?(attribute) || super
+          end
+        end
+      end
+    end
+  end
+end

lib/sequencer/unit/exchange/connection.rb

@@ -1,14 +1,14 @@
 class Sequencer
   class Unit
     module Exchange
-      class Connection < Sequencer::Unit::Common::FallbackProvider
+      class Connection < Sequencer::Unit::Common::Provider::Fallback
 
         uses :ews_config
         provides :ews_connection
 
         private
 
-        def fallback
+        def ews_connection
           Viewpoint::EWSClient.new(
             config[:endpoint],
             config[:user],

lib/sequencer/unit/import/exchange/folder_contacts/folder_ids.rb

@@ -3,13 +3,13 @@ class Sequencer
     module Import
       module Exchange
         module FolderContacts
-          class FolderIds < Sequencer::Unit::Common::FallbackProvider
+          class FolderIds < Sequencer::Unit::Common::Provider::Fallback
 
             provides :ews_folder_ids
 
             private
 
-            def fallback
+            def ews_folder_ids
               ::Import::Exchange.config[:folders]
             end
           end

lib/sequencer/unit/ldap/config.rb

@@ -3,12 +3,13 @@ require 'import/ldap'
 class Sequencer
   class Unit
     module Ldap
-      class Config < Sequencer::Unit::Common::FallbackProvider
+      class Config < Sequencer::Unit::Common::Provider::Fallback
+
         provides :ldap_config
 
         private
 
-        def fallback
+        def ldap_config
           ::Import::Ldap.config
         end
       end

lib/sequencer/unit/ldap/connection.rb

@@ -3,13 +3,14 @@ require 'ldap'
 class Sequencer
   class Unit
     module Ldap
-      class Connection < Sequencer::Unit::Common::FallbackProvider
+      class Connection < Sequencer::Unit::Common::Provider::Fallback
+
         uses :ldap_config
         provides :ldap_connection
 
         private
 
-        def fallback
+        def ldap_connection
           ::Ldap.new(ldap_config)
         end
       end