Access controls refers to the methods which allow you to set the access to classes, methods and other members. They are used to encapsulate the components so that we can maintain security of these methods throughout the project.

Ruby gives us three types of access controls namely : 

1. Public 
2. Protected
3. Private

Public

• A public method can be called by everyone in which no access control is required. This purely means that every instance of the class can call them. All methods are public by default except initialize which is private by default.

class Cars
  def car_name
    "Audi A9"   
  end
private
  def car_type
   "SUV"
 end
protected
  def car_chasis_number
   "ABCDE12345"
 end
end

c = Car.new
c.car_name      #This will be called successfully.
c.car_type      #This Will give an access violation error
c.car_chasis_number #This will give an access violation error

Private

• A private method cant be accessed outside the class and only class methods can access private members. That means private method can be called only by the current objects or we can say self. Hence private method can be called from within a class it is declared in as well as all subclasses of this class.

class A

  def main_function
  function1
end

private
  def function1
   puts "hello from #{self.class}"
 end
end

class B < A
  def main_function
  function1
end
end

A.new.main_function #This will be called successfully and the output will be hello from A  
B.new.main_function #This will be called successfully and the output will be hello from B

Protected

• Protected methods are also similar to private methods that they can be called by the objects of the class in which they are declared or the subclass of the class in which they are cleared but the difference is they can be called explicitly if the caller is a self method.

class A

  def main_function
    function1
end

  protected
  def function1
   puts "hello from #{self.class}"
 end
 end

class B < A

  def main_function
  function1
end
end

class C < A

  def main_function
  self.function1
end
end

A.new.main_function #This will be called successfully and the output will give Hello from A 
B.new.main_function #This will be called successfully and the output will give Hello from B 
C.new.main_function #This will be called successfully and the output will give Hello from C