Add support for callbacks

4 files changed, 975 insertions, 0 deletions

diff --git a/activesupport/lib/active_support.rb b/activesupport/lib/active_support.rb
index 62d538e2d5..dbd30f9271 100644
--- a/activesupport/lib/active_support.rb
+++ b/activesupport/lib/active_support.rb
@@ -32,6 +32,7 @@ module ActiveSupport
   autoload :BufferedLogger, 'active_support/buffered_logger'
   autoload :Cache, 'active_support/cache'
   autoload :Callbacks, 'active_support/callbacks'
+  autoload :NewCallbacks, 'active_support/new_callbacks'
   autoload :ConcurrentHash, 'active_support/concurrent_hash'
   autoload :Deprecation, 'active_support/deprecation'
   autoload :Duration, 'active_support/duration'
diff --git a/activesupport/lib/active_support/new_callbacks.rb b/activesupport/lib/active_support/new_callbacks.rb
new file mode 100644
index 0000000000..cf717bfbb9
--- /dev/null
+++ b/activesupport/lib/active_support/new_callbacks.rb
@@ -0,0 +1,477 @@
+module ActiveSupport
+  # Callbacks are hooks into the lifecycle of an object that allow you to trigger logic
+  # before or after an alteration of the object state.
+  #
+  # Mixing in this module allows you to define callbacks in your class.
+  #
+  # Example:
+  #   class Storage
+  #     include ActiveSupport::Callbacks
+  #
+  #     define_callbacks :save
+  #   end
+  #
+  #   class ConfigStorage < Storage
+  #     save_callback :before, :saving_message
+  #     def saving_message
+  #       puts "saving..."
+  #     end
+  #
+  #     save_callback :after do |object|
+  #       puts "saved"
+  #     end
+  #
+  #     def save
+  #       _run_save_callbacks do
+  #         puts "- save"
+  #       end
+  #     end
+  #   end
+  #
+  #   config = ConfigStorage.new
+  #   config.save
+  #
+  # Output:
+  #   saving...
+  #   - save
+  #   saved
+  #
+  # Callbacks from parent classes are inherited.
+  #
+  # Example:
+  #   class Storage
+  #     include ActiveSupport::Callbacks
+  #
+  #     define_callbacks :save
+  #
+  #     save_callback :before, :prepare
+  #     def prepare
+  #       puts "preparing save"
+  #     end
+  #   end
+  #
+  #   class ConfigStorage < Storage
+  #     save_callback :before, :saving_message
+  #     def saving_message
+  #       puts "saving..."
+  #     end
+  #
+  #     save_callback :after do |object|
+  #       puts "saved"
+  #     end
+  #
+  #     def save
+  #       _run_save_callbacks do
+  #         puts "- save"
+  #       end
+  #     end
+  #   end
+  #
+  #   config = ConfigStorage.new
+  #   config.save
+  #
+  # Output:
+  #   preparing save
+  #   saving...
+  #   - save
+  #   saved
+  module NewCallbacks
+    def self.included(klass)
+      klass.extend ClassMethods
+    end
+        
+    def run_callbacks(kind, options = {}, &blk)
+      send("_run_#{kind}_callbacks", &blk)
+    end
+    
+    class Callback
+      @@_callback_sequence = 0
+      
+      attr_accessor :filter, :kind, :name, :options, :per_key, :klass
+      def initialize(filter, kind, options, klass, name)
+        @kind, @klass = kind, klass
+        @name         = name
+        
+        normalize_options!(options)
+
+        @per_key              = options.delete(:per_key)
+        @raw_filter, @options = filter, options
+        @filter               = _compile_filter(filter)
+        @compiled_options     = _compile_options(options)
+        @callback_id          = next_id
+
+        _compile_per_key_options
+      end
+      
+      def clone(klass)
+        obj                  = super()
+        obj.klass            = klass
+        obj.per_key          = @per_key.dup
+        obj.options          = @options.dup
+        obj.per_key[:if]     = @per_key[:if].dup
+        obj.per_key[:unless] = @per_key[:unless].dup
+        obj.options[:if]     = @options[:if].dup
+        obj.options[:unless] = @options[:unless].dup
+        obj
+      end
+      
+      def normalize_options!(options)
+        options[:if] = Array(options[:if])
+        options[:unless] = Array(options[:unless])
+
+        options[:per_key] ||= {}
+        options[:per_key][:if] = Array(options[:per_key][:if])
+        options[:per_key][:unless] = Array(options[:per_key][:unless])
+      end
+      
+      def next_id
+        @@_callback_sequence += 1
+      end
+      
+      def matches?(_kind, _name, _filter)
+        @kind   == _kind &&
+        @name   == _name &&
+        @filter == _filter
+      end
+
+      def _update_filter(filter_options, new_options)
+        filter_options[:if].push(new_options[:unless]) if new_options.key?(:unless)
+        filter_options[:unless].push(new_options[:if]) if new_options.key?(:if)
+      end
+            
+      def recompile!(_options, _per_key)
+        _update_filter(self.options, _options)
+        _update_filter(self.per_key, _per_key)
+        
+        @callback_id      = next_id
+        @filter           = _compile_filter(@raw_filter)
+        @compiled_options = _compile_options(@options)
+                            _compile_per_key_options
+      end
+
+      def _compile_per_key_options
+        key_options  = _compile_options(@per_key)
+
+        @klass.class_eval <<-RUBY_EVAL, __FILE__, __LINE__ + 1
+          def _one_time_conditions_valid_#{@callback_id}?
+            true #{key_options[0]}
+          end
+        RUBY_EVAL
+      end
+      
+      # This will supply contents for before and around filters, and no
+      # contents for after filters (for the forward pass).
+      def start(key = nil, options = {})
+        object, terminator = (options || {}).values_at(:object, :terminator)
+        
+        return if key && !object.send("_one_time_conditions_valid_#{@callback_id}?")
+        
+        terminator ||= false
+        
+        # options[0] is the compiled form of supplied conditions
+        # options[1] is the "end" for the conditional
+                
+        if @kind == :before || @kind == :around
+          if @kind == :before
+            # if condition    # before_save :filter_name, :if => :condition
+            #   filter_name
+            # end
+            filter = <<-RUBY_EVAL
+              unless halted
+                result = #{@filter}
+                halted ||= (#{terminator})
+              end
+            RUBY_EVAL
+            [@compiled_options[0], filter, @compiled_options[1]].compact.join("\n")
+          else
+            # Compile around filters with conditions into proxy methods
+            # that contain the conditions.
+            #
+            # For `around_save :filter_name, :if => :condition':
+            #
+            # def _conditional_callback_save_17
+            #   if condition
+            #     filter_name do
+            #       yield self
+            #     end
+            #   else
+            #     yield self
+            #   end
+            # end
+            
+            name = "_conditional_callback_#{@kind}_#{next_id}"
+            txt = <<-RUBY_EVAL
+              def #{name}(halted)
+                #{@compiled_options[0] || "if true"} && !halted
+                  #{@filter} do
+                    yield self
+                  end
+                else
+                  yield self
+                end
+              end
+            RUBY_EVAL
+            @klass.class_eval(txt)
+            "#{name}(halted) do"
+          end
+        end
+      end
+      
+      # This will supply contents for around and after filters, but not
+      # before filters (for the backward pass).
+      def end(key = nil, options = {})
+        object = (options || {})[:object]
+        
+        return if key && !object.send("_one_time_conditions_valid_#{@callback_id}?")
+        
+        if @kind == :around || @kind == :after
+          # if condition    # after_save :filter_name, :if => :condition
+          #   filter_name
+          # end
+          if @kind == :after
+            [@compiled_options[0], @filter, @compiled_options[1]].compact.join("\n")
+          else
+            "end"
+          end
+        end
+      end
+      
+      private
+      # Options support the same options as filters themselves (and support
+      # symbols, string, procs, and objects), so compile a conditional
+      # expression based on the options
+      def _compile_options(options)        
+        return [] if options[:if].empty? && options[:unless].empty?
+        
+        conditions = []
+        
+        unless options[:if].empty?
+          conditions << Array(_compile_filter(options[:if]))
+        end
+        
+        unless options[:unless].empty?
+          conditions << Array(_compile_filter(options[:unless])).map {|f| "!#{f}"}
+        end
+        
+        ["if #{conditions.flatten.join(" && ")}", "end"]
+      end
+      
+      # Filters support:
+      #   Arrays::  Used in conditions. This is used to specify
+      #             multiple conditions. Used internally to
+      #             merge conditions from skip_* filters
+      #   Symbols:: A method to call
+      #   Strings:: Some content to evaluate
+      #   Procs::   A proc to call with the object
+      #   Objects:: An object with a before_foo method on it to call
+      #
+      # All of these objects are compiled into methods and handled
+      # the same after this point:
+      #   Arrays::  Merged together into a single filter
+      #   Symbols:: Already methods
+      #   Strings:: class_eval'ed into methods
+      #   Procs::   define_method'ed into methods
+      #   Objects:: 
+      #     a method is created that calls the before_foo method
+      #     on the object.
+      def _compile_filter(filter)
+        method_name = "_callback_#{@kind}_#{next_id}"
+        case filter
+        when Array
+          filter.map {|f| _compile_filter(f)}
+        when Symbol
+          filter
+        when Proc
+          @klass.send(:define_method, method_name, &filter)
+          method_name << (filter.arity == 1 ? "(self)" : "")
+        when String
+          @klass.class_eval <<-RUBY_EVAL
+            def #{method_name}
+              #{filter}
+            end
+          RUBY_EVAL
+          method_name
+        else
+          kind, name = @kind, @name
+          @klass.send(:define_method, method_name) do
+            filter.send("#{kind}_#{name}", self)
+          end
+          method_name
+        end
+      end
+    end
+
+    # This method_missing is supplied to catch callbacks with keys and create
+    # the appropriate callback for future use.
+    def method_missing(meth, *args, &blk)
+      if meth.to_s =~ /_run__([\w:]+)__(\w+)__(\w+)__callbacks/
+        return self.class._create_and_run_keyed_callback($1, $2.to_sym, $3.to_sym, self, &blk)
+      end
+      super
+    end
+    
+    # An Array with a compile method
+    class CallbackChain < Array
+      def initialize(symbol)
+        @symbol = symbol
+      end
+      
+      def compile(key = nil, options = {})
+        method = []
+        method << "halted = false"
+        each do |callback|
+          method << callback.start(key, options)
+        end
+        method << "yield self if block_given?"
+        reverse_each do |callback|
+          method << callback.end(key, options)
+        end
+        method.compact.join("\n")
+      end
+      
+      def clone(klass)
+        chain = CallbackChain.new(@symbol)
+        chain.push(*map {|c| c.clone(klass)})
+      end
+    end
+        
+    module ClassMethods
+      CHAINS = {:before => :before, :around => :before, :after => :after}
+      
+      # Make the _run_save_callbacks method. The generated method takes
+      # a block that it'll yield to. It'll call the before and around filters
+      # in order, yield the block, and then run the after filters.
+      # 
+      # _run_save_callbacks do
+      #   save
+      # end
+      #
+      # The _run_save_callbacks method can optionally take a key, which
+      # will be used to compile an optimized callback method for each
+      # key. See #define_callbacks for more information.
+      def _define_runner(symbol, str, options)
+        str = <<-RUBY_EVAL
+          def _run_#{symbol}_callbacks(key = nil)
+            if key
+              send("_run__\#{self.class.name.split("::").last}__#{symbol}__\#{key}__callbacks") { yield if block_given? }
+            else
+              #{str}
+            end
+          end
+        RUBY_EVAL
+  
+        class_eval str, __FILE__, __LINE__ + 1
+        
+        before_name, around_name, after_name = 
+          options.values_at(:before, :after, :around)
+      end
+      
+      # This is called the first time a callback is called with a particular
+      # key. It creates a new callback method for the key, calculating
+      # which callbacks can be omitted because of per_key conditions.
+      def _create_and_run_keyed_callback(klass, kind, key, obj, &blk)
+        @_keyed_callbacks ||= {}
+        @_keyed_callbacks[[kind, key]] ||= begin
+          str = self.send("_#{kind}_callbacks").compile(key, :object => obj, :terminator => self.send("_#{kind}_terminator"))
+                              
+          self.class_eval <<-RUBY_EVAL, __FILE__, __LINE__ + 1
+            def _run__#{klass.split("::").last}__#{kind}__#{key}__callbacks
+              #{str}
+            end
+          RUBY_EVAL
+                    
+          true
+        end
+                                  
+        obj.send("_run__#{klass.split("::").last}__#{kind}__#{key}__callbacks", &blk)
+      end
+      
+      # Define callbacks.
+      #
+      # Creates a <name>_callback method that you can use to add callbacks.
+      #
+      # Syntax:
+      #   save_callback :before, :before_meth
+      #   save_callback :after,  :after_meth, :if => :condition
+      #   save_callback :around {|r| stuff; yield; stuff }
+      #
+      # The <name>_callback method also updates the _run_<name>_callbacks
+      # method, which is the public API to run the callbacks.
+      #
+      # Also creates a skip_<name>_callback method that you can use to skip
+      # callbacks.
+      #
+      # When creating or skipping callbacks, you can specify conditions that
+      # are always the same for a given key. For instance, in ActionPack,
+      # we convert :only and :except conditions into per-key conditions.
+      #
+      #   before_filter :authenticate, :except => "index"
+      # becomes
+      #   dispatch_callback :before, :authenticate, :per_key => {:unless => proc {|c| c.action_name == "index"}}
+      #
+      # Per-Key conditions are evaluated only once per use of a given key.
+      # In the case of the above example, you would do:
+      #
+      #   run_dispatch_callbacks(action_name) { ... dispatch stuff ... }
+      #
+      # In that case, each action_name would get its own compiled callback
+      # method that took into consideration the per_key conditions. This
+      # is a speed improvement for ActionPack.
+      def define_callbacks(*symbols)
+        terminator = symbols.pop if symbols.last.is_a?(String)
+        symbols.each do |symbol|
+          self.class_inheritable_accessor("_#{symbol}_terminator")
+          self.send("_#{symbol}_terminator=", terminator)
+          self.class_eval <<-RUBY_EVAL, __FILE__, __LINE__ + 1
+            class_inheritable_accessor :_#{symbol}_callbacks
+            self._#{symbol}_callbacks = CallbackChain.new(:#{symbol})
+
+            def self.#{symbol}_callback(*filters, &blk)
+              type = [:before, :after, :around].include?(filters.first) ? filters.shift : :before
+              options = filters.last.is_a?(Hash) ? filters.pop : {}
+              filters.unshift(blk) if block_given?
+              
+              filters.map! do |filter| 
+                # overrides parent class
+                self._#{symbol}_callbacks.delete_if {|c| c.matches?(type, :#{symbol}, filter)}
+                Callback.new(filter, type, options.dup, self, :#{symbol})
+              end
+              self._#{symbol}_callbacks.push(*filters)
+              _define_runner(:#{symbol}, 
+                self._#{symbol}_callbacks.compile(nil, :terminator => _#{symbol}_terminator), 
+                options)
+            end
+            
+            def self.skip_#{symbol}_callback(*filters, &blk)
+              type = [:before, :after, :around].include?(filters.first) ? filters.shift : :before
+              options = filters.last.is_a?(Hash) ? filters.pop : {}
+              filters.unshift(blk) if block_given?
+              filters.each do |filter|
+                self._#{symbol}_callbacks = self._#{symbol}_callbacks.clone(self)
+                
+                filter = self._#{symbol}_callbacks.find {|c| c.matches?(type, :#{symbol}, filter) }
+                per_key = options[:per_key] || {}
+                if filter
+                  filter.recompile!(options, per_key)
+                else
+                  self._#{symbol}_callbacks.delete(filter)
+                end
+                _define_runner(:#{symbol}, 
+                  self._#{symbol}_callbacks.compile(nil, :terminator => _#{symbol}_terminator), 
+                  options)
+              end
+              
+            end
+            
+            def self.reset_#{symbol}_callbacks
+              self._#{symbol}_callbacks = CallbackChain.new(:#{symbol})
+              _define_runner(:#{symbol}, self._#{symbol}_callbacks.compile, {})
+            end
+            
+            self.#{symbol}_callback(:before)
+          RUBY_EVAL
+        end
+      end
+    end
+  end
+end
diff --git a/activesupport/test/new_callback_inheritance_test.rb b/activesupport/test/new_callback_inheritance_test.rb
new file mode 100644
index 0000000000..95020389b0
--- /dev/null
+++ b/activesupport/test/new_callback_inheritance_test.rb
@@ -0,0 +1,115 @@
+require 'test/unit'
+$:.unshift "#{File.dirname(__FILE__)}/../lib"
+require 'active_support'
+
+class GrandParent
+  include ActiveSupport::NewCallbacks
+  
+  attr_reader :log, :action_name
+  def initialize(action_name)
+    @action_name, @log = action_name, []
+  end
+  
+  define_callbacks :dispatch
+  dispatch_callback :before, :before1, :before2, :per_key => {:if => proc {|c| c.action_name == "index" || c.action_name == "update" }}
+  dispatch_callback :after, :after1, :after2, :per_key => {:if => proc {|c| c.action_name == "update" || c.action_name == "delete" }}  
+  
+  def before1
+    @log << "before1"
+  end
+  
+  def before2
+    @log << "before2"
+  end
+  
+  def after1 
+    @log << "after1"
+  end
+  
+  def after2
+    @log << "after2"
+  end
+  
+  def dispatch
+    _run_dispatch_callbacks(action_name) do
+      @log << action_name
+    end
+    self
+  end
+end
+
+class Parent < GrandParent
+  skip_dispatch_callback :before, :before2, :per_key => {:unless => proc {|c| c.action_name == "update" }}
+  skip_dispatch_callback :after, :after2, :per_key => {:unless => proc {|c| c.action_name == "delete" }}
+end
+
+class Child < GrandParent
+  skip_dispatch_callback :before, :before2, :per_key => {:unless => proc {|c| c.action_name == "update" }}, :if => :state_open?
+  
+  def state_open?
+    @state == :open
+  end
+  
+  def initialize(action_name, state)
+    super(action_name)
+    @state = state
+  end
+end
+
+
+class BasicCallbacksTest < Test::Unit::TestCase
+  def setup
+    @index    = GrandParent.new("index").dispatch
+    @update   = GrandParent.new("update").dispatch
+    @delete   = GrandParent.new("delete").dispatch
+    @unknown  = GrandParent.new("unknown").dispatch
+  end
+  
+  def test_basic_per_key1
+    assert_equal %w(before1 before2 index), @index.log
+  end
+  
+  def test_basic_per_key2
+    assert_equal %w(before1 before2 update after2 after1), @update.log
+  end
+  
+  def test_basic_per_key3
+    assert_equal %w(delete after2 after1), @delete.log
+  end
+end
+
+class InheritedCallbacksTest < Test::Unit::TestCase
+  def setup
+    @index    = Parent.new("index").dispatch
+    @update   = Parent.new("update").dispatch
+    @delete   = Parent.new("delete").dispatch
+    @unknown  = Parent.new("unknown").dispatch
+  end
+  
+  def test_inherited_excluded
+    assert_equal %w(before1 index), @index.log
+  end
+  
+  def test_inherited_not_excluded
+    assert_equal %w(before1 before2 update after1), @update.log
+  end
+  
+  def test_partially_excluded
+    assert_equal %w(delete after2 after1), @delete.log
+  end
+end
+
+class InheritedCallbacksTest2 < Test::Unit::TestCase
+  def setup
+    @update1 = Child.new("update", :open).dispatch
+    @update2 = Child.new("update", :closed).dispatch
+  end
+  
+  def test_crazy_mix_on
+    assert_equal %w(before1 update after2 after1), @update1.log
+  end
+  
+  def test_crazy_mix_off
+    assert_equal %w(before1 before2 update after2 after1), @update2.log
+  end
+end
\ No newline at end of file
diff --git a/activesupport/test/new_callbacks_test.rb b/activesupport/test/new_callbacks_test.rb
new file mode 100644
index 0000000000..6948ad23dc
--- /dev/null
+++ b/activesupport/test/new_callbacks_test.rb
@@ -0,0 +1,382 @@
+# require 'abstract_unit'
+require 'test/unit'
+$:.unshift "#{File.dirname(__FILE__)}/../lib"
+require 'active_support'
+
+class Record
+  include ActiveSupport::NewCallbacks
+
+  define_callbacks :save
+  
+  def self.before_save(*filters, &blk)
+    save_callback(:before, *filters, &blk)
+  end
+  
+  def self.after_save(*filters, &blk)
+    save_callback(:after, *filters, &blk)
+  end
+
+  class << self
+    def callback_symbol(callback_method)
+      returning(:"#{callback_method}_method") do |method_name|
+        define_method(method_name) do
+          history << [callback_method, :symbol]
+        end
+      end
+    end
+
+    def callback_string(callback_method)
+      "history << [#{callback_method.to_sym.inspect}, :string]"
+    end
+
+    def callback_proc(callback_method)
+      Proc.new { |model| model.history << [callback_method, :proc] }
+    end
+
+    def callback_object(callback_method)
+      klass = Class.new
+      klass.send(:define_method, callback_method) do |model|
+        model.history << [callback_method, :object]
+      end
+      klass.new
+    end
+  end
+
+  def history
+    @history ||= []
+  end
+end
+
+class Person < Record
+  [:before_save, :after_save].each do |callback_method|
+    callback_method_sym = callback_method.to_sym
+    send(callback_method, callback_symbol(callback_method_sym))
+    send(callback_method, callback_string(callback_method_sym))
+    send(callback_method, callback_proc(callback_method_sym))
+    send(callback_method, callback_object(callback_method_sym))
+    send(callback_method) { |model| model.history << [callback_method_sym, :block] }
+  end
+
+  def save
+    _run_save_callbacks {}
+  end
+end
+
+class PersonSkipper < Person
+  skip_save_callback :before, :before_save_method, :if => :yes
+  skip_save_callback :after, :before_save_method, :unless => :yes
+  skip_save_callback :after, :before_save_method, :if => :no
+  skip_save_callback :before, :before_save_method, :unless => :no
+  def yes; true; end
+  def no; false; end
+end
+
+class ParentController
+  include ActiveSupport::NewCallbacks
+
+  define_callbacks :dispatch
+    
+  dispatch_callback :before, :log, :per_key => {:unless => proc {|c| c.action_name == :index || c.action_name == :show }}
+  dispatch_callback :after, :log2
+  
+  attr_reader :action_name, :logger
+  def initialize(action_name)
+    @action_name, @logger = action_name, []
+  end
+  
+  def log
+    @logger << action_name
+  end
+  
+  def log2
+    @logger << action_name
+  end
+  
+  def dispatch
+    _run_dispatch_callbacks(action_name) {
+      @logger << "Done"
+    }
+    self
+  end
+end
+
+class Child < ParentController
+  skip_dispatch_callback :before, :log, :per_key => {:if => proc {|c| c.action_name == :update} }
+  skip_dispatch_callback :after, :log2
+end
+
+class OneTimeCompile < Record
+  @@starts_true, @@starts_false = true, false
+  
+  def initialize
+    super
+  end
+  
+  before_save Proc.new {|r| r.history << [:before_save, :starts_true, :if] }, :per_key => {:if => :starts_true}
+  before_save Proc.new {|r| r.history << [:before_save, :starts_false, :if] }, :per_key => {:if => :starts_false}
+  before_save Proc.new {|r| r.history << [:before_save, :starts_true, :unless] }, :per_key => {:unless => :starts_true}
+  before_save Proc.new {|r| r.history << [:before_save, :starts_false, :unless] }, :per_key => {:unless => :starts_false}
+  
+  def starts_true
+    if @@starts_true
+      @@starts_true = false
+      return true
+    end
+    @@starts_true
+  end
+  
+  def starts_false
+    unless @@starts_false
+      @@starts_false = true
+      return false
+    end
+    @@starts_false
+  end
+  
+  def save
+    _run_save_callbacks(:action) {}
+  end
+end
+
+class OneTimeCompileTest < Test::Unit::TestCase
+  def test_optimized_first_compile
+    around = OneTimeCompile.new
+    around.save
+    assert_equal [
+      [:before_save, :starts_true, :if],
+      [:before_save, :starts_true, :unless]
+    ], around.history
+  end
+end
+
+class ConditionalPerson < Record
+  # proc
+  before_save Proc.new { |r| r.history << [:before_save, :proc] }, :if => Proc.new { |r| true }
+  before_save Proc.new { |r| r.history << "b00m" }, :if => Proc.new { |r| false }
+  before_save Proc.new { |r| r.history << [:before_save, :proc] }, :unless => Proc.new { |r| false }
+  before_save Proc.new { |r| r.history << "b00m" }, :unless => Proc.new { |r| true }
+  # symbol
+  before_save Proc.new { |r| r.history << [:before_save, :symbol] }, :if => :yes
+  before_save Proc.new { |r| r.history << "b00m" }, :if => :no
+  before_save Proc.new { |r| r.history << [:before_save, :symbol] }, :unless => :no
+  before_save Proc.new { |r| r.history << "b00m" }, :unless => :yes
+  # string
+  before_save Proc.new { |r| r.history << [:before_save, :string] }, :if => 'yes'
+  before_save Proc.new { |r| r.history << "b00m" }, :if => 'no'
+  before_save Proc.new { |r| r.history << [:before_save, :string] }, :unless => 'no'
+  before_save Proc.new { |r| r.history << "b00m" }, :unless => 'yes'
+  # Combined if and unless
+  before_save Proc.new { |r| r.history << [:before_save, :combined_symbol] }, :if => :yes, :unless => :no
+  before_save Proc.new { |r| r.history << "b00m" }, :if => :yes, :unless => :yes
+
+  def yes; true; end
+  def other_yes; true; end
+  def no; false; end
+  def other_no; false; end
+
+  def save
+    _run_save_callbacks {}
+  end
+end
+
+class MySuper
+  include ActiveSupport::NewCallbacks
+  define_callbacks :save
+end
+
+class AroundPerson < MySuper
+  attr_reader :history
+  
+  save_callback :before, :nope,           :if =>     :no
+  save_callback :before, :nope,           :unless => :yes
+  save_callback :after,  :tweedle
+  save_callback :before, "tweedle_dee"
+  save_callback :before, proc {|m| m.history << "yup" }
+  save_callback :before, :nope,           :if =>     proc { false }
+  save_callback :before, :nope,           :unless => proc { true }
+  save_callback :before, :yup,            :if =>     proc { true }
+  save_callback :before, :yup,            :unless => proc { false }
+  save_callback :around, :tweedle_dum
+  save_callback :around, :w0tyes,         :if =>     :yes
+  save_callback :around, :w0tno,          :if =>     :no
+  save_callback :around, :tweedle_deedle
+  
+  def no; false; end
+  def yes; true; end
+  
+  def nope
+    @history << "boom"
+  end
+  
+  def yup
+    @history << "yup"
+  end
+  
+  def w0tyes
+    @history << "w0tyes before"
+    yield
+    @history << "w0tyes after"
+  end
+  
+  def w0tno
+    @history << "boom"
+    yield
+  end
+  
+  def tweedle_dee
+    @history << "tweedle dee"
+  end
+  
+  def tweedle_dum
+    @history << "tweedle dum pre"
+    yield
+    @history << "tweedle dum post"
+  end
+  
+  def tweedle
+    @history << "tweedle"
+  end
+  
+  def tweedle_deedle
+    @history << "tweedle deedle pre"
+    yield
+    @history << "tweedle deedle post"
+  end
+  
+  def initialize
+    @history = []
+  end
+  
+  def save
+    _run_save_callbacks do
+      @history << "running"
+    end
+  end
+end
+
+class AroundCallbacksTest < Test::Unit::TestCase
+  def test_save_around
+    around = AroundPerson.new
+    around.save
+    assert_equal [
+      "tweedle dee",
+      "yup", "yup", "yup",
+      "tweedle dum pre",
+      "w0tyes before",
+      "tweedle deedle pre",
+      "running",
+      "tweedle deedle post",
+      "w0tyes after",
+      "tweedle dum post",
+      "tweedle"
+    ], around.history
+  end
+end
+
+class SkipCallbacksTest < Test::Unit::TestCase
+  def test_skip_person
+    person = PersonSkipper.new
+    assert_equal [], person.history
+    person.save
+    assert_equal [
+      [:before_save, :string],
+      [:before_save, :proc],
+      [:before_save, :object],
+      [:before_save, :block],
+      [:after_save, :block],
+      [:after_save, :object],
+      [:after_save, :proc],
+      [:after_save, :string],
+      [:after_save, :symbol]
+    ], person.history
+  end
+end
+
+class CallbacksTest < Test::Unit::TestCase
+  def test_save_person
+    person = Person.new
+    assert_equal [], person.history
+    person.save
+    assert_equal [
+      [:before_save, :symbol],
+      [:before_save, :string],
+      [:before_save, :proc],
+      [:before_save, :object],
+      [:before_save, :block],
+      [:after_save, :block],
+      [:after_save, :object],
+      [:after_save, :proc],
+      [:after_save, :string],
+      [:after_save, :symbol]
+    ], person.history
+  end
+end
+
+class ConditionalCallbackTest < Test::Unit::TestCase
+  def test_save_conditional_person
+    person = ConditionalPerson.new
+    person.save
+    assert_equal [
+      [:before_save, :proc],
+      [:before_save, :proc],
+      [:before_save, :symbol],
+      [:before_save, :symbol],
+      [:before_save, :string],
+      [:before_save, :string],
+      [:before_save, :combined_symbol],
+    ], person.history
+  end
+end
+
+class CallbackTerminator
+  include ActiveSupport::NewCallbacks
+  
+  define_callbacks :save, "result == :halt"
+  
+  save_callback :before, :first
+  save_callback :before, :second
+  save_callback :around, :around_it  
+  save_callback :before, :third
+  save_callback :after, :first
+  save_callback :around, :around_it
+  save_callback :after, :second
+  save_callback :around, :around_it
+  save_callback :after, :third
+
+  
+  attr_reader :history
+  def initialize
+    @history = []
+  end
+  
+  def around_it
+    @history << "around1"
+    yield
+    @history << "around2"
+  end
+  
+  def first
+    @history << "first"
+  end
+  
+  def second
+    @history << "second"
+    :halt
+  end
+  
+  def third
+    @history << "third"
+  end
+  
+  def save
+    _run_save_callbacks
+  end
+end
+
+class CallbackTerminatorTest < Test::Unit::TestCase
+  def test_termination
+    terminator = CallbackTerminator.new
+    terminator.save
+    assert_equal ["first", "second", "third", "second", "first"], terminator.history
+  end
+end