1 files changed, 91 insertions, 0 deletions
diff --git a/activemodel/lib/active_model/callbacks.rb b/activemodel/lib/active_model/callbacks.rb
new file mode 100644
index 0000000000..f66a1ddcaa
--- /dev/null
+++ b/activemodel/lib/active_model/callbacks.rb
@@ -0,0 +1,91 @@
+require 'active_support/callbacks'
+
+module ActiveModel
+  module Callbacks
+    def self.extended(base)
+      base.class_eval do
+        include ActiveSupport::Callbacks
+      end
+    end
+
+    # Define callbacks similar to ActiveRecord ones. It means:
+    #
+    # * The callback chain is aborted whenever the block given to
+    #   _run_callbacks returns false.
+    #
+    # * If a class is given to the fallback, it will search for
+    #   before_create, around_create and after_create methods.
+    #
+    # == Usage
+    #
+    # First you need to define which callbacks your model will have:
+    #
+    #   class MyModel
+    #     define_model_callbacks :create
+    #   end
+    #
+    # This will define three class methods: before_create, around_create,
+    # and after_create. They accept a symbol, a string, an object or a block.
+    #
+    # After you create a callback, you need to tell when they are executed.
+    # For example, you could do:
+    #
+    #   def create
+    #     _run_create_callbacks do
+    #       super
+    #     end
+    #   end
+    # 
+    # == Options
+    #
+    # define_model_callbacks accepts all options define_callbacks does, in
+    # case you want to overwrite a default. Besides that, it also accepts
+    # an :only option, where you can choose if you want all types (before,
+    # around or after) or just some:
+    #
+    #   define_model_callbacks :initializer, :only => :after
+    #
+    def define_model_callbacks(*callbacks)
+      options = callbacks.extract_options!
+      options = { :terminator => "result == false", :scope => [:kind, :name] }.merge(options)
+
+      types = Array(options.delete(:only))
+      types = [:before, :around, :after] if types.empty?
+
+      callbacks.each do |callback|
+        define_callbacks(callback, options)
+
+        types.each do |type|
+          send(:"_define_#{type}_model_callback", self, callback)
+        end
+      end
+    end
+
+    def _define_before_model_callback(klass, callback) #:nodoc:
+      klass.class_eval <<-CALLBACK, __FILE__, __LINE__
+        def self.before_#{callback}(*args, &block)
+          set_callback(:#{callback}, :before, *args, &block)
+        end
+      CALLBACK
+    end
+
+    def _define_around_model_callback(klass, callback) #:nodoc:
+      klass.class_eval <<-CALLBACK, __FILE__, __LINE__
+        def self.around_#{callback}(*args, &block)
+          set_callback(:#{callback}, :around, *args, &block)
+        end
+      CALLBACK
+    end
+
+    def _define_after_model_callback(klass, callback) #:nodoc:
+      klass.class_eval <<-CALLBACK, __FILE__, __LINE__
+        def self.after_#{callback}(*args, &block)
+          options = args.extract_options!
+          options[:prepend] = true
+          options[:if] = Array(options[:if]) << "!halted && value != false"
+          set_callback(:#{callback}, :after, *(args << options), &block)
+        end
+      CALLBACK
+    end
+  end
+end
+\ No newline at end of file