CODEWITHSUNDEEP
javaruby-on-railsrubyinterface
grizzthedj
grizzthedj

Reputation: 7505

Is there a way to enforce the implementation of interface methods in Ruby?

I'm currently developing a central authentication API(in ruby on rails) which will authenticate with many other providers based on the domain of a user's email address.

If I was using java, this would be a classic use case for interfaces. Given that I am using Ruby, I would still like to use the interface construct, but not really sure how to enforce the implementation of interface methods.

The intention for this interface is to have one authenticated? method, for now at least.

An example implementation. It authenticates a user in a local database. 

# internal_user.rb
class InternalUser < User
  def authenticated?(email, password)
    user = User.find_for_database_authentication(email: email)
    user && user.valid_password?(password) && !user.confirmed_at.nil?
  end
end

So when I add more provider support to my API(i.e. more classes that implement this interface), how can I ensure that these new classes are going to implement this interface, in other words, ensure that the authenticated? method has been implemented?

Upvotes: 1

Views: 1082

Answers (1)

Eric Duminil
Eric Duminil

Reputation: 54263

Ruby doesn't have any interface similar to Java. With duck-typing, it's up to each class to decide if it answers a method call or not.

If you want to show that a method should be implemented in a subclass, you could raise an exception in the parent method :

class User
  def authenticated?(*p)
    raise NotImplementedError, "IMPLEMENT ME IN #{self.class}##{__method__}"
  end
end

class InternalUser < User
end

InternalUser.new.authenticated?('user', '[email protected]')
#interface.rb:3:in `authenticated?': IMPLEMENT ME IN InternalUser#authenticated? (NotImplementedError)

Upvotes: 3

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