adding basic ability module

LICENSE

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+Copyright (c) 2009 Ryan Bates
+
+Permission is hereby granted, free of charge, to any person obtaining
+a copy of this software and associated documentation files (the
+"Software"), to deal in the Software without restriction, including
+without limitation the rights to use, copy, modify, merge, publish,
+distribute, sublicense, and/or sell copies of the Software, and to
+permit persons to whom the Software is furnished to do so, subject to
+the following conditions:
+
+The above copyright notice and this permission notice shall be
+included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

README

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+= Render Caching
+
+Cache render calls in Rails controllers.
+
+
+== Install
+
+First install the gem.
+
+  gem install ryanb-render-caching --source=http://gems.github.com
+
+Then specify it in your Rails config.
+
+	config.gem 'ryanb-render-caching', :lib => 'render_caching', :source => 'http://gems.github.com'
+
+Rails 2.1 or later required.
+
+
+== Usage
+
+This gem adds the render_with_cache method to all controllers. Call 
+this inside of an action to cache the view.
+
+	def show
+	  @user = User.find(params[:id])
+	  render_with_cache
+	end
+
+This will cache the full rendered contents into a key matching the URL 
+path (similar to action caching). You can change this key by simply 
+passing any parameter.
+
+	def show
+	  @user = User.find(params[:id])
+	  render_with_cache @user.cache_key
+	end
+
+Cache key is a method supplied by Rails. This includes the updated_at 
+time which will give you an auto-expiring cache when the user record is 
+updated.
+
+You can also supply a block to the render call which will only get 
+executed if there is no cache. Here is a good place to do any custom 
+render calls.
+
+	def show
+	  @user = User.find(params[:id])
+	  render_with_cache @user.cache_key do
+	    render :layout => false
+	  end
+	end
+
+
+== Development
+
+This project can be found on github at the following URL.
+
+http://github.com/ryanb/render-caching/
+
+If you would like to contribute to this project, please fork the 
+repository and send me a pull request.

Rakefile

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+require 'rubygems'
+require 'rake'
+require 'spec/rake/spectask'
+
+spec_files = Rake::FileList["spec/**/*_spec.rb"]
+
+desc "Run specs"
+Spec::Rake::SpecTask.new do |t|
+  t.spec_files = spec_files
+  t.spec_opts = ["-c"]
+end

lib/cancan.rb

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+$:.unshift(File.dirname(__FILE__))
+require 'cancan/ability'

lib/cancan/ability.rb

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+module CanCan
+  module Ability
+    def self.included(base)
+      base.extend ClassMethods
+    end
+    
+    def can?(action, target)
+      self.class.can_history.reverse.each do |can_action, can_target, can_block|
+        if can_action == action && (can_target == :all || can_target == target || target.kind_of?(can_target))
+          if can_block.nil?
+            return true
+          else
+            if can_target == :all
+              if target.class == Class
+                return can_block.call(target, nil)
+              else
+                return can_block.call(target.class, target)
+              end
+            elsif can_target == target
+              return can_block.call(nil)
+            else
+              return can_block.call(target)
+            end
+          end
+        end
+      end
+      false
+    end
+    
+    module ClassMethods
+      attr_reader :can_history
+      
+      def can(action, target, &block)
+        @can_history ||= []
+        @can_history << [action, target, block]
+      end
+    end
+  end
+end

spec/cancan/ability_spec.rb

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+require File.dirname(__FILE__) + '/../spec_helper'
+
+class Ability
+  include CanCan::Ability
+  can :read, :all
+  can :read, Symbol do |sym|
+    sym
+  end
+  can :preview, :all do |object_class, object|
+    [object_class, object]
+  end
+end
+
+describe CanCan::Ability do
+  before(:each) do
+    @ability = Ability.new
+  end
+  
+  it "should be able to :read anything" do
+    @ability.can?(:read, String).should be_true
+    @ability.can?(:read, 123).should be_true
+  end
+  
+  it "should not have permission to do something it doesn't know about" do
+    @ability.can?(:foodfight, String).should be_false
+  end
+  
+  it "should return what block returns on a can call" do
+    @ability.can?(:read, Symbol).should be_nil
+    @ability.can?(:read, :some_symbol).should == :some_symbol
+  end
+  
+  it "should pass class with object if :all objects are accepted" do
+    @ability.can?(:preview, 123).should == [Fixnum, 123]
+  end
+  
+  it "should pass class with no object if :all objects are accepted and class is passed directly" do
+    @ability.can?(:preview, Hash).should == [Hash, nil]
+  end
+end

spec/spec_helper.rb

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+require 'rubygems'
+require 'spec'
+require 'active_support'
+require 'active_record'
+require 'action_controller'
+require 'action_view'
+require File.dirname(__FILE__) + '/../lib/cancan.rb'
+
+Spec::Runner.configure do |config|
+  config.mock_with :rr
+end