removed more boiler-plate

6 files changed, 12 insertions, 37 deletions

diff --git a/lib/arel/relations/operations/join.rb b/lib/arel/relations/operations/join.rb
index 01fa6da255..243a0289c7 100644
--- a/lib/arel/relations/operations/join.rb
+++ b/lib/arel/relations/operations/join.rb
@@ -5,7 +5,7 @@ module Arel
     delegate :engine, :name, :to => :relation1
     hash_on :relation1
 
-    def initialize(join_sql, relation1, relation2 = Nil.new, *predicates)
+    def initialize(join_sql, relation1, relation2 = Nil.instance, *predicates)
       @join_sql, @relation1, @relation2, @predicates = join_sql, relation1, relation2, predicates
     end
     
diff --git a/lib/arel/relations/utilities/aggregation.rb b/lib/arel/relations/utilities/aggregation.rb
index 66150bff0a..9f5ead8f86 100644
--- a/lib/arel/relations/utilities/aggregation.rb
+++ b/lib/arel/relations/utilities/aggregation.rb
@@ -1,11 +1,9 @@
 module Arel
   class Aggregation < Compound
+    attributes :relation
+    deriving :initialize, :==
     include Recursion::BaseCase
 
-    def initialize(relation)
-      @relation = relation
-    end
-    
     def wheres
       []
     end
@@ -21,11 +19,6 @@ module Arel
     def name
       relation.name + '_aggregation'
     end
-    
-    def ==(other)
-      Aggregation   === other and
-      self.relation ==  other.relation
-    end
   end
   
   class Relation
diff --git a/lib/arel/relations/utilities/nil.rb b/lib/arel/relations/utilities/nil.rb
index 2dcfb47233..2b8dc570f8 100644
--- a/lib/arel/relations/utilities/nil.rb
+++ b/lib/arel/relations/utilities/nil.rb
@@ -1,10 +1,8 @@
 module Arel
   class Nil < Relation
+    include Singleton
+    
     def table_sql(formatter = nil); '' end
     def name; '' end
-
-    def ==(other)
-      Nil === other
-    end
   end
 end
\ No newline at end of file
diff --git a/lib/arel/relations/writes/delete.rb b/lib/arel/relations/writes/delete.rb
index 2eaad6d1da..e72679c4d6 100644
--- a/lib/arel/relations/writes/delete.rb
+++ b/lib/arel/relations/writes/delete.rb
@@ -1,8 +1,7 @@
 module Arel
   class Deletion < Compound
-    def initialize(relation)
-      @relation = relation
-    end
+    attributes :relation
+    deriving :initialize, :==
 
     def to_sql(formatter = nil)
       [
@@ -16,10 +15,5 @@ module Arel
     def call(connection = engine.connection)
       connection.delete(to_sql)
     end
-    
-    def ==(other)
-      Deletion    === other and
-      relation    ==  other.relation
-    end
   end
 end
\ No newline at end of file
diff --git a/lib/arel/relations/writes/insert.rb b/lib/arel/relations/writes/insert.rb
index a1c4c93de5..0545d7faa3 100644
--- a/lib/arel/relations/writes/insert.rb
+++ b/lib/arel/relations/writes/insert.rb
@@ -1,6 +1,7 @@
 module Arel
   class Insert < Compound
-    attr_reader :record
+    attributes :relation, :record
+    deriving :==
 
     def initialize(relation, record)
       @relation, @record = relation, record.bind(relation)
@@ -18,11 +19,5 @@ module Arel
     def call(connection = engine.connection)
       connection.insert(to_sql)
     end
-    
-    def ==(other)
-      Insert   === other         and
-      relation    == other.relation and
-      record      == other.record
-    end
   end
 end
\ No newline at end of file
diff --git a/lib/arel/relations/writes/update.rb b/lib/arel/relations/writes/update.rb
index 760f4e931f..18b7ad9de1 100644
--- a/lib/arel/relations/writes/update.rb
+++ b/lib/arel/relations/writes/update.rb
@@ -1,7 +1,8 @@
 module Arel
   class Update < Compound
-    attr_reader :assignments
-
+    attributes :relation, :assignments
+    deriving :==
+    
     def initialize(relation, assignments)
       @relation, @assignments = relation, assignments.bind(relation)
     end
@@ -20,11 +21,5 @@ module Arel
     def call(connection = engine.connection)
       connection.update(to_sql)
     end
-    
-    def ==(other)
-      Update      === other          and
-      relation    ==  other.relation and
-      assignments ==  other.assignments
-    end
   end
 end
\ No newline at end of file