From 2a7b686b0b01ed2e642ab73143aab2f3bc33d6f1 Mon Sep 17 00:00:00 2001
From: Nikita Afanasenko <nikita@afanasenko.name>
Date: Sun, 31 Mar 2013 13:48:21 +0400
Subject: [PATCH] Implement proxy class methods caching.

Now we have a proxy classes with the methods predefined to prevent
tons of `method_missing` calls.
---
 lib/attr_ability/model/instance_proxy.rb      | 51 +++++++++++++++----
 lib/attr_ability/model_additions.rb           |  2 +-
 .../attr_ability/model/instance_proxy_spec.rb | 38 ++++++++++++++
 3 files changed, 79 insertions(+), 12 deletions(-)
 create mode 100644 spec/attr_ability/model/instance_proxy_spec.rb

diff --git a/lib/attr_ability/model/instance_proxy.rb b/lib/attr_ability/model/instance_proxy.rb
index bd138ac..8fcfabb 100644
--- a/lib/attr_ability/model/instance_proxy.rb
+++ b/lib/attr_ability/model/instance_proxy.rb
@@ -1,20 +1,49 @@
 module AttrAbility
   module Model
-    class InstanceProxy
-      instance_methods.each { |m| undef_method m unless m =~ /(^__|^send$|^object_id$)/ }
+    module InstanceProxy
+      @@initialization_mutex = Mutex.new
 
-      def initialize(model, sanitizer)
-        @model = model
-        @sanitizer = sanitizer
+      def self.[](klass)
+        @@initialization_mutex.synchronize do
+          @_proxy_classes ||= {}
+          @_proxy_classes[klass] ||= Class.new do
+            include ProxyMethods
+          end
+        end
       end
 
-      protected
+      module ProxyMethods
+        extend ActiveSupport::Concern
 
-      def method_missing(name, *args, &block)
-        @model.mass_assignment_sanitizer = @sanitizer
-        @model.send(name, *args, &block)
-      ensure
-        @model.mass_assignment_sanitizer = nil
+        included do
+          alias __proxy_class__ class
+          instance_methods.each { |m| undef_method m unless m =~ /(^__|^send$|^object_id$|^initialize$|^method_missing$)/ }
+        end
+
+        def initialize(model, sanitizer)
+          @model = model
+          @sanitizer = sanitizer
+        end
+
+        protected
+
+        def method_missing(name, *args, &block)
+          delegate_method(name)
+          self.send(name, *args, &block)
+        end
+
+        private
+
+        def delegate_method(name)
+          __proxy_class__.class_eval <<-METHOD, __FILE__, __LINE__ + 1
+            def #{name}(*args, &block)
+              @model.mass_assignment_sanitizer = @sanitizer
+              @model.#{name}(*args, &block)
+            ensure
+              @model.mass_assignment_sanitizer = nil
+            end
+          METHOD
+        end
       end
     end
   end
diff --git a/lib/attr_ability/model_additions.rb b/lib/attr_ability/model_additions.rb
index a5b7c62..34999b7 100644
--- a/lib/attr_ability/model_additions.rb
+++ b/lib/attr_ability/model_additions.rb
@@ -62,7 +62,7 @@ def ability(action, attributes)
     end
 
     def as(ability)
-      AttrAbility::Model::InstanceProxy.new(self, self.class.build_sanitizer(ability))
+      AttrAbility::Model::InstanceProxy[self.class].new(self, self.class.build_sanitizer(ability))
     end
 
     def as_system
diff --git a/spec/attr_ability/model/instance_proxy_spec.rb b/spec/attr_ability/model/instance_proxy_spec.rb
new file mode 100644
index 0000000..a5dec19
--- /dev/null
+++ b/spec/attr_ability/model/instance_proxy_spec.rb
@@ -0,0 +1,38 @@
+require 'spec_helper'
+
+describe AttrAbility::Model::InstanceProxy do
+  with_model :ProxyPost do
+    table do |t|
+      t.string :title
+      t.integer :author_id
+      t.string :status
+    end
+  end
+
+  with_model :ProxyAuthor do
+    table do |t|
+      t.string :name
+    end
+  end
+
+  subject { AttrAbility::Model::InstanceProxy }
+  let(:sanitizer) { AttrAbility::Model::Sanitizer.new(SanitizerTestAbility.new(:system)) }
+  let(:post) { ProxyPost.new(title: "some") }
+  let(:author) { ProxyAuthor.new(name: "some") }
+  let(:proxied_post) { subject[ProxyPost].new(post, sanitizer) }
+  let(:proxied_author) { subject[ProxyAuthor].new(author, sanitizer) }
+
+  it "caches class" do
+    subject[ProxyPost] == subject[ProxyPost]
+  end
+
+  it "proxies methods" do
+    proxied_post.title.should == post.title
+  end
+
+  it "does not leak methods to another model" do
+    # ensure post cached
+    proxied_post.title
+    proxied_author.methods.should_not include(:title)
+  end
+end