just use a hash for doing association caching

Author: tenderlove

activerecord/lib/active_record/associations.rb

@@ -132,24 +132,24 @@ module Associations # :nodoc:
 
     # Clears out the association cache.
     def clear_association_cache #:nodoc:
-      self.class.reflect_on_all_associations.to_a.each do |assoc|
-        instance_variable_set "@#{assoc.name}", nil
-      end if persisted?
+      @association_cache.clear if persisted?
     end
 
+    # :nodoc:
+    attr_reader :association_cache
+
     private
       # Returns the specified association instance if it responds to :loaded?, nil otherwise.
       def association_instance_get(name)
-        ivar = "@#{name}"
-        if instance_variable_defined?(ivar)
-          association = instance_variable_get(ivar)
+        if @association_cache.key? name
+          association = @association_cache[name]
           association if association.respond_to?(:loaded?)
         end
       end
 
       # Set the specified association instance.
       def association_instance_set(name, association)
-        instance_variable_set("@#{name}", association)
+        @association_cache[name] = association
       end
 
     # Associations are a set of macro-like class methods for tying objects together through

activerecord/lib/active_record/associations/class_methods/join_dependency.rb

@@ -176,7 +176,7 @@ def construct(parent, associations, join_parts, row)
 
             join_part = join_parts.detect { |j|
               j.reflection.name.to_s == name &&
-                j.parent_table_name    == parent.class.table_name }
+                j.parent_table_name == parent.class.table_name }
 
               raise(ConfigurationError, "No such association") unless join_part
 
@@ -201,7 +201,7 @@ def construct_association(record, join_part, row)
 
           macro = join_part.reflection.macro
           if macro == :has_one
-            return if record.instance_variable_defined?("@#{join_part.reflection.name}")
+            return if record.association_cache.key?(join_part.reflection.name)
             association = join_part.instantiate(row) unless row[join_part.aliased_primary_key].nil?
             set_target_and_inverse(join_part, association, record)
           else

activerecord/lib/active_record/base.rb

@@ -1368,6 +1368,7 @@ def encode_quoted_value(value) #:nodoc:
       # hence you can't have attributes that aren't part of the table columns.
       def initialize(attributes = nil)
         @attributes = attributes_from_column_definition
+        @association_cache = {}
         @attributes_cache = {}
         @new_record = true
         @readonly = false
@@ -1415,6 +1416,7 @@ def encode_with(coder)
       def init_with(coder)
         @attributes = coder['attributes']
         @attributes_cache, @previously_changed, @changed_attributes = {}, {}, {}
+        @association_cache = {}
         @readonly = @destroyed = @marked_for_destruction = false
         @new_record = false
         _run_find_callbacks
@@ -1627,8 +1629,9 @@ def initialize_dup(other)
         end
 
         clear_aggregation_cache
-        clear_association_cache
-        @attributes_cache   = {}
+
+        @association_cache = {}
+        @attributes_cache = {}
         @new_record  = true
 
         ensure_proper_type

activerecord/test/cases/associations/belongs_to_associations_test.rb

@@ -78,14 +78,14 @@ def test_eager_loading_with_primary_key
     Firm.create("name" => "Apple")
     Client.create("name" => "Citibank", :firm_name => "Apple")
     citibank_result = Client.find(:first, :conditions => {:name => "Citibank"}, :include => :firm_with_primary_key)
-    assert_not_nil citibank_result.instance_variable_get("@firm_with_primary_key")
+    assert citibank_result.association_cache.key?(:firm_with_primary_key)
   end
 
   def test_eager_loading_with_primary_key_as_symbol
     Firm.create("name" => "Apple")
     Client.create("name" => "Citibank", :firm_name => "Apple")
     citibank_result = Client.find(:first, :conditions => {:name => "Citibank"}, :include => :firm_with_primary_key_symbols)
-    assert_not_nil citibank_result.instance_variable_get("@firm_with_primary_key_symbols")
+    assert citibank_result.association_cache.key?(:firm_with_primary_key_symbols)
   end
 
   def test_creating_the_belonging_object

activerecord/test/cases/inheritance_test.rb

@@ -203,7 +203,7 @@ def test_alt_complex_inheritance
 
   def test_eager_load_belongs_to_something_inherited
     account = Account.find(1, :include => :firm)
-    assert_not_nil account.instance_variable_get("@firm"), "nil proves eager load failed"
+    assert account.association_cache.key?(:firm), "nil proves eager load failed"
   end
 
   def test_eager_load_belongs_to_primary_key_quoting

activerecord/test/cases/modules_test.rb

@@ -49,7 +49,6 @@ def test_associations_spanning_cross_modules
 
   def test_find_account_and_include_company
     account = MyApplication::Billing::Account.find(1, :include => :firm)
-    assert_kind_of MyApplication::Business::Firm, account.instance_variable_get('@firm')
     assert_kind_of MyApplication::Business::Firm, account.firm
   end