kan_example.rb

module Post
  class AnonymousAbilities
    include Kan::Abilities

    role(:anonymous) do |user, _|
      user.id.nil?
    end

    register(:read) { [] }
  end

  class BaseAbilities
    include Kan::Abilities

    role(:all) do |_, _|
      !!user.id
    end

    register(:read) { |user, repo| repo.all_with_limit(user) }
  end


  class PayedUserAbilities
    include Kan::Abilities

    role(:author) do |user, post|
      !!user.id and user.payed
    end

    register(:read) { |user, repo| repo.all(user) }
  end
end

abilities = Kan::Application.new(
  post: [Post::AnonymousAbilities.new, Post::BaseAbilities.new, Post::PayedUserAbilities.new]
)

abilities['post.read'].call(anonymous, post) # => []
abilities['post.read'].call(regular, post)   # => [5 items]
abilities['post.read'].call(payed, post)    # => [all items]