How you can break up large Ability class in CanCan

abilities.rb

module Abilities
  def self.ability_for(user)
    if user.admin?
      AdminAbility.new(user)
    else user
      MemberAbility.new(user)
    else
      GuestAbility.new
    end
  end

  class AdminAbility
    include CanCan::Ability

    def initialize(user)
      # ...
    end
  end

  class MemberAbility
    include CanCan::Ability

    def initialize(user)
      # ...
    end
  end

  class GuestAbility
    include CanCan::Ability

    def initialize(user)
      # ...
    end
  end

  # move classes into separate files as needed if they get too long
end

application_controller.rb

def current_ability
  @current_ability ||= Abilities.ability_for(current_user)
end

Thanks for this! How would you do if some permissions are not mutually exclusive - i.e. a User has different roles? For example, an Admin should have permissions defined in AdminAbility and also the ones in MemberAbility.

How would you do if some permissions are not mutually exclusive ..?

An example from @dgilperez using Ability#merge.