Backporting the modifications for Rails 3 to Rails 2.3

lib/paperclip.rb

@@ -36,6 +36,7 @@ require 'paperclip/storage'
 require 'paperclip/interpolations'
 require 'paperclip/style'
 require 'paperclip/attachment'
+require 'paperclip/callback_compatability'
 if defined?(Rails.root) && Rails.root
   Dir.glob(File.join(File.expand_path(Rails.root), "lib", "paperclip_processors", "*.rb")).each do |processor|
     require processor
@@ -111,6 +112,13 @@ module Paperclip
 
     def included base #:nodoc:
       base.extend ClassMethods
+      if base.respond_to?("set_callback")
+        base.send :include, Paperclip::CallbackCompatability::Rails3
+      elsif !base.respond_to?("define_callbacks")
+        base.send :include, Paperclip::CallbackCompatability::Rails20
+      else
+        base.send :include, Paperclip::CallbackCompatability::Rails21
+      end
     end
 
     def processor name #:nodoc:
@@ -314,22 +322,6 @@ module Paperclip
     def attachment_definitions
       read_inheritable_attribute(:attachment_definitions)
     end
-
-    private
-
-    def define_paperclip_callbacks(*callbacks)
-      define_callbacks *[callbacks, {:terminator => "result == false"}].flatten
-      callbacks.each do |callback|
-        eval <<-end_callbacks
-          def before_#{callback}(*args, &blk)
-            set_callback(:#{callback}, :before, *args, &blk)
-          end
-          def after_#{callback}(*args, &blk)
-            set_callback(:#{callback}, :after, *args, &blk)
-          end
-        end_callbacks
-      end
-    end
   end
 
   module InstanceMethods #:nodoc:

lib/paperclip/attachment.rb

@@ -280,8 +280,8 @@ module Paperclip
 
     def post_process #:nodoc:
       return if @queued_for_write[:original].nil?
-      instance.run_callbacks(:post_process) do
-        instance.run_callbacks(:"#{name}_post_process") do
+      instance.run_paperclip_callbacks(:post_process) do
+        instance.run_paperclip_callbacks(:"#{name}_post_process") do
           post_process_styles
         end
       end

lib/paperclip/callback_compatability.rb

@@ -2,32 +2,80 @@ module Paperclip
   # This module is intended as a compatability shim for the differences in
   # callbacks between Rails 2.0 and Rails 2.1.
   module CallbackCompatability
+    module Rails20
       def self.included(base)
-      base.extend(ClassMethods)
-      base.send(:include, InstanceMethods)
+        base.extend(Defining)
+        base.send(:include, Running)
+        puts "Including Rails 2.0 Compatability"
       end
 
-    module ClassMethods
-      # The implementation of this method is taken from the Rails 1.2.6 source,
-      # from rails/activerecord/lib/active_record/callbacks.rb, line 192.
-      def define_callbacks(*args)
-        args.each do |method|
-          self.class_eval <<-"end_eval"
-            def self.#{method}(*callbacks, &block)
-              callbacks << block if block_given?
-              write_inheritable_array(#{method.to_sym.inspect}, callbacks)
+      module Defining
+        def define_paperclip_callbacks(*args)
         end
-          end_eval
       end
+
+      module Running
+        def run_paperclip_callbacks(callback, opts = nil, &blk)
+        end
+      end
+    end
+
+    module Rails21
+      def self.included(base)
+        base.extend(Defining)
+        base.send(:include, Running)
+      end
+
+      module Defining
+        def define_paperclip_callbacks(*args)
+          args.each do |callback|
+            define_callbacks("before_#{callback}")
+            define_callbacks("after_#{callback}")
+          end
+        end
+      end
+
+      module Running
+        def run_paperclip_callbacks(callback, opts = nil, &blk)
+          # The overall structure of this isn't ideal since after callbacks run even if
+          # befores return false. But this is how rails 3's callbacks work, unfortunately.
+          if run_callbacks(:"before_#{callback}"){ |result, object| result == false } != false
+            blk.call
+          end
+          run_callbacks(:"after_#{callback}"){ |result, object| result == false }
         end
       end
+    end
+
+    module Rails3
+      def self.included(base)
+        base.extend(Defining)
+        base.send(:include, Running)
+      end
 
-    module InstanceMethods
-      # The callbacks in < 2.1 don't worry about the extra options or the
-      # block, so just run what we have available.
-      def run_callbacks(meth, opts = nil, &blk)
-        callback(meth)
+      module Defining
+        def define_paperclip_callbacks(*callbacks)
+          define_callbacks *[callbacks, {:terminator => "result == false"}].flatten
+          callbacks.each do |callback|
+            eval <<-end_callbacks
+              def before_#{callback}(*args, &blk)
+                set_callback(:#{callback}, :before, *args, &blk)
+              end
+              def after_#{callback}(*args, &blk)
+                set_callback(:#{callback}, :after, *args, &blk)
+              end
+            end_callbacks
+          end
         end
       end
+
+      module Running
+        def run_paperclip_callbacks(callback, opts = nil, &block)
+          run_callbacks(callback, opts, &block)
+        end
+      end
+
+    end
+
   end
 end

test/attachment_test.rb

@@ -399,12 +399,17 @@ class AttachmentTest < Test::Unit::TestCase
     end
 
     should "cancel the processing if a before_post_process returns false" do
+      begin
+      $DEBUG = true
       @dummy.expects(:do_before_avatar).never
       @dummy.expects(:do_after_avatar).never
       @dummy.expects(:do_before_all).with().returns(false)
       @dummy.expects(:do_after_all)
       Paperclip::Thumbnail.expects(:make).never
       @dummy.avatar = @file
+    ensure
+      $DEBUG = false
+    end
     end
 
     should "cancel the processing if a before_avatar_post_process returns false" do

test/helper.rb

@@ -8,8 +8,9 @@ require 'mocha'
 
 gem 'sqlite3-ruby'
 
-require 'active_record'
-require 'active_support'
+require 'activerecord'
+require 'activesupport'
+require 'actionpack'
 begin
   require 'ruby-debug'
 rescue LoadError
@@ -94,8 +95,9 @@ class FakeModel
     @errors ||= []
   end
 
-  def run_callbacks name, *args
+  def run_paperclip_callbacks name, *args
   end
+
 end
 
 def attachment options