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Description: Ruby on Rails
Homepage: http://rubyonrails.org
Clone URL: git://github.com/rails/rails.git 
Allow memoized methods to be reloaded and allow multiple symbols
josh (author)
Fri Jul 18 09:18:16 -0700 2008
commit  e1f23da53cef20a60e4bf458d959fe2bfe7d52ea
tree    97753d4e40ef08da5c0827b51e03a4e7f5c8c276
parent  7430c4168fad07b480dbf80c8ac75ba7db8c634f
0
activesupport/lib/active_support/memoizable.rb 
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@@ -5,28 +5,30 @@ module ActiveSupport
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     end
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     module ClassMethods
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-      def memoize(symbol)
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-        original_method = "_unmemoized_#{symbol}"
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-        memoized_ivar = "@_memoized_#{symbol}"
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-        raise "Already memoized #{symbol}" if instance_methods.map(&:to_s).include?(original_method)
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+      def memoize(*symbols)
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+        symbols.each do |symbol|
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+          original_method = "unmemoized_#{symbol}"
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+          memoized_ivar = "@#{symbol}"
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+          raise "Already memoized #{symbol}" if instance_methods.map(&:to_s).include?(original_method)
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-        alias_method original_method, symbol
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-        class_eval <<-EOS, __FILE__, __LINE__
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-          def #{symbol}
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-            if defined? #{memoized_ivar}
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-              #{memoized_ivar}
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-            else
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-              #{memoized_ivar} = #{original_method}
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+          alias_method original_method, symbol
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+          class_eval <<-EOS, __FILE__, __LINE__
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+            def #{symbol}(reload = false)
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+              if !reload && defined? #{memoized_ivar}
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+                #{memoized_ivar}
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+              else
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+                #{memoized_ivar} = #{original_method}.freeze
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+              end
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             end
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-          end
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-        EOS
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+          EOS
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+        end
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       end
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     end
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     def freeze
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       methods.each do |method|
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-        if m = method.to_s.match(/\A_unmemoized_(.*)/)
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-          send(m[1]).freeze
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+        if m = method.to_s.match(/\Aunmemoized_(.*)/)
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+          send(m[1])
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         end
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       end
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       super
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activesupport/test/memoizable_test.rb 
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@@ -8,12 +8,16 @@ uses_mocha 'Memoizable' do
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       def name
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         fetch_name_from_floppy
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       end
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-      memoize :name
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       def age
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         nil
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       end
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-      memoize :age
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+
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+      def random
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+        rand(0)
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+      end
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+
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+      memoize :name, :age, :random
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       private
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         def fetch_name_from_floppy
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@@ -21,25 +25,34 @@ uses_mocha 'Memoizable' do
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         end
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     end
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+    def setup
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+      @person = Person.new
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+    end
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+
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     def test_memoization
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-      person = Person.new
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-      assert_equal "Josh", person.name
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+      assert_equal "Josh", @person.name
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+
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+      @person.expects(:fetch_name_from_floppy).never
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+      2.times { assert_equal "Josh", @person.name }
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+    end
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-      person.expects(:fetch_name_from_floppy).never
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-      2.times { assert_equal "Josh", person.name }
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+    def test_reloadable
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+      random = @person.random
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+      assert_equal random, @person.random
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+      assert_not_equal random, @person.random(:reload)
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     end
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     def test_memoized_methods_are_frozen
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-      person = Person.new
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-      person.freeze
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-      assert_equal "Josh", person.name
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-      assert_equal true, person.name.frozen?
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+      assert_equal true, @person.name.frozen?
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+
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+      @person.freeze
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+      assert_equal "Josh", @person.name
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+      assert_equal true, @person.name.frozen?
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     end
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     def test_memoization_frozen_with_nil_value
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-      person = Person.new
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-      person.freeze
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-      assert_equal nil, person.age
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+      @person.freeze
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+      assert_equal nil, @person.age
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     end
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     def test_double_memoization

Comments

DefV Fri Jul 18 09:24:14 -0700 2008 at activesupport/test/memoizable_test.rb L48

This test will not always pass :-)

NZKoz Fri Jul 18 11:51:59 -0700 2008

Unless it’s run on debian

nbibler Fri Jul 18 12:01:10 -0700 2008

It would probably be better to replace the random calls with an incrementing instance variable. For instance:

class Person
  def current_count
    @count ||= 0
    @count += 1
  end
  memoize :current_count

You can then reliably test expected values against the memoization.

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