Private methods in Ruby

Question

An example of Rails controller which defines a private method:

class ApplicationController < ActionController::Base
  private
  def authorization_method
    # do something
  end
end

Then, it's being used in a subclass of ApplicationController:

class CustomerController < ApplicatioController
  before_action :authorization_method

  # controller actions
end

How is it possible that a private method is called from its subclass? What is the meaning of private in Ruby?

Answer 1

Private methods cannot be called with an explicit receiver. But they can be called by any subclasses and instances of the class.

Here's a nice explanation of public, protected and private methods in Ruby.

Answer 2

What private does in Ruby, unlike in other languages, is make so that methods can not be called with explicit receiver.

Aka, you can't call some_variable.some_private_method or even self.some_private_method.

That is all. They are still inherited. You can read more here.