Use Rails 3 callbacks.

These callbacks are different from pre-rails 3. They do NOT cancel the
after_ if the before_ returns false. They will cancell inner callbacks,
however, but that's it. This is a change in functionality.

lib/paperclip.rb

@@ -46,7 +46,7 @@
 # documentation for Paperclip::ClassMethods for more useful information.
 module Paperclip
 
-  VERSION = "2.3.1.1"
+  VERSION = "2.3.2"
 
   class << self
     # Provides configurability to Paperclip. There are a number of options available, such as:
@@ -111,9 +111,6 @@ def bit_bucket #:nodoc:
 
     def included base #:nodoc:
       base.extend ClassMethods
-      unless base.respond_to?(:define_callbacks)
-        base.send(:include, Paperclip::CallbackCompatability)
-      end
     end
 
     def processor name #:nodoc:
@@ -222,9 +219,8 @@ def has_attached_file name, options = {}
       after_save :save_attached_files
       before_destroy :destroy_attached_files
 
-      define_callbacks :before_post_process, :after_post_process
-      define_callbacks :"before_#{name}_post_process", :"after_#{name}_post_process"
-
+      define_paperclip_callbacks :post_process, :"#{name}_post_process"
+
       define_method name do |*args|
         a = attachment_for(name)
         (args.length > 0) ? a.to_s(args.first) : a
@@ -318,6 +314,22 @@ def validates_attachment_content_type name, options = {}
     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

@@ -280,18 +280,11 @@ def extra_options_for(style) #:nodoc:
 
     def post_process #:nodoc:
       return if @queued_for_write[:original].nil?
-      return if fire_events(:before)
-      post_process_styles
-      return if fire_events(:after)
-    end
-
-    def fire_events(which) #:nodoc:
-      return true if callback(:"#{which}_post_process") == false
-      return true if callback(:"#{which}_#{name}_post_process") == false
-    end
-
-    def callback which #:nodoc:
-      instance.run_callbacks(which, @queued_for_write)
+      instance.run_callbacks(:post_process) do
+        instance.run_callbacks(:"#{name}_post_process") do
+          post_process_styles
+        end
+      end
     end
 
     def post_process_styles #:nodoc:

test/attachment_test.rb

@@ -362,7 +362,7 @@ class Paperclip::Test < Paperclip::Processor; end
 
   context "Assigning an attachment with post_process hooks" do
     setup do
-      rebuild_model :styles => { :something => "100x100#" }
+      rebuild_class :styles => { :something => "100x100#" }
       Dummy.class_eval do
         before_avatar_post_process :do_before_avatar
         after_avatar_post_process :do_after_avatar
@@ -402,16 +402,16 @@ def do_after_all; end
       @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).never
+      @dummy.expects(:do_after_all)
       Paperclip::Thumbnail.expects(:make).never
       @dummy.avatar = @file
     end
 
     should "cancel the processing if a before_avatar_post_process returns false" do
       @dummy.expects(:do_before_avatar).with().returns(false)
-      @dummy.expects(:do_after_avatar).never
+      @dummy.expects(:do_after_avatar)
       @dummy.expects(:do_before_all).with().returns(true)
-      @dummy.expects(:do_after_all).never
+      @dummy.expects(:do_after_all)
       Paperclip::Thumbnail.expects(:make).never
       @dummy.avatar = @file
     end