permissionable

Permissionable is distributed as a gem. To install, just add this line to your Gemfile:
gem 'permissionable', '~> 0.1.3'

Hooking up your model is as easy as including Permissionable and defining your permission schema

include Permissionable
permissions read: 1,
            write: 2,
            delete: 3

Your model doesn't have to be an ActiveRecord (AR) model, but Permissionable works out of the box with AR to persist the permissions. Just throw in a permissions_integer column in the mix.

class AddPermissionsToResource < ActiveRecord::Migration
  def change
    add_column :resources, :permissions_integer, :integer
  end
end

If your're not using AR can also implement your own #read_attribute and #update_column methods to handle read_attribute(:permissions_integer) and update_column(:permissions_integer, permissions_integer)

To check if your permissionable resource has a certain permission, use the [] method which will return true or false.

For instance, to check if your user has permission to :read_books,
user.permissions[:read_books]

You can also specify multiple permissions, which will check to see if your resource has all of the permissions provided (I.e. it will return false if any of the permissions are missing).
user.permissions[:read_books, :delete_books]

Note if you find the permissions[:read_books, :delete_books] syntax awkward, you can also use #include?
user.permissions.include?(:read_books, :delete_books)

You can add permissions to your resource with the familiar "append to"-syntax. To add permissions to :read_books to your user:
user.permissions << :read_books

You can also add an array of permissions yo your array of permissions:
user.permissions << [:read_books, :delete_books]

Note Again, if special syntax like this isn't really your cup of tea, you can also use #add
user.permissions.add(:read_books, :delete_books)

Removing permissions from your resource is pretty straight forward:
user.permissions.remove(:delete_books)

Or, if you would like to remove all permissions:
user.permissions.clear!

class User < ActiveRecord::Base
  include Permissionable
  
  permissions read: 1,
              write: 2,
              delete: 3
end

user = User.create
user.permissions[:read] # => false
user.permissions << :read
user.permissions[:read] # => true
user.permissions[:read, :write] # => false
user.permissions << :write
user.permissions[:read, :write] # => true
user.permissions.remove(:read)
user.permissions[:read, :write] # => false